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Abstract:

Provided herein are methods and systems to produce a bicarbonate solution
from one or more of natural substances and to contact the bicarbonate
solution with cathode electrolyte in an electrochemical system to produce
a product containing carbonate or combination of carbonate and
bicarbonate.

Claims:

1. A method comprising: contacting an anode with an anode electrolyte,
contacting a cathode with a cathode electrolyte, deriving a bicarbonate
solution from one or more of natural substances; contacting the
bicarbonate solution with the cathode electrolyte, and applying a voltage
across the anode and the cathode.

2. The method of claim 1, wherein the one or more of natural substances
is selected from the group consisting of naturally occurring brines
including subterranean, subsurface and surface brines, crystalline
shoreline or bottom crusts, shallow lake bottom crusts, surface
efflorescence, minerals, solutions obtained after the mining of the ores,
evaporite, and lakes.

3. The method of claim 1, wherein the subterranean brine is selected from
the group consisting of bicarbonate brine, carbonate brine, alkaline
brine, and combination thereof.

4. The method of claim 1, wherein the bicarbonate solution is derived
from an evaporite comprising bicarbonate, carbonate, or combination
thereof.

5. The method of claim 1, wherein the bicarbonate solution is derived by
contacting carbon dioxide with a carbonate brine.

7. The method of claim 1, wherein the bicarbonate solution is derived by
dissolving carbon dioxide into an alkaline brine.

8. The method of claim 1, wherein the bicarbonate solution is derived by
dissolving carbon dioxide in one or more of natural substances wherein
the carbon dioxide is an industrial waste stream comprising flue gas from
combustion; a flue gas from a chemical processing plant; a flue gas from
a plant that produces CO2 as a byproduct; or combination thereof.

9. The method of claim 1, wherein the bicarbonate solution is derived
from a naturally occurring bicarbonate brine.

10. The method of claim 1, further comprising producing hydroxide ions in
the cathode electrolyte and hydrochloric acid or sulfuric acid in the
anode electrolyte on applying the voltage across the anode and the
cathode.

11. The method of claim 10, wherein the method produces carbonate ions by
contacting the bicarbonate solution with the hydroxide in the cathode
electrolyte.

12. The method of claim 1, further comprising producing a pH difference
of between 4-12 pH units between the anode electrolyte and the cathode
electrolyte when a voltage of 0.05-1V is applied between the anode and
the cathode.

13. The method of claim 11, further comprising treating bicarbonate
and/or carbonate ions with a divalent cation selected from the group
consisting of calcium, magnesium, and combination thereof to form a
cementitious material.

14. A system comprising: an electrochemical system comprising an anode
electrolyte in contact with an anode and a cathode electrolyte in contact
with a cathode; a reactor system configured to produce a bicarbonate
solution from one or more of natural substances wherein the one or more
of natural substances is selected from the group consisting of naturally
occurring brines including subterranean, subsurface and surface brines,
crystalline shoreline or bottom crusts, shallow lake bottom crusts,
surface efflorescence, minerals, solutions obtained after the mining of
the ores, evaporite, and lakes; and a contact system operably connected
to the cathode electrolyte of the electrochemical system and configured
to contact the bicarbonate solution from the reactor system with the
cathode electrolyte.

15. The system of claim 14, wherein the electrochemical system is
configured to produce hydroxide ions and hydrogen gas in the cathode
electrolyte and an acid in the anode electrolyte on applying a voltage
across the anode and the cathode.

16. The system of claim 15, wherein the cathode electrolyte and the anode
electrolyte are separated by an ion exchange membrane and the
electrochemical system is configured to direct hydrogen gas from the
cathode to the anode.

17. The system of claim 14, wherein the system is configured to produce
carbonate ions by a reaction of the bicarbonate ions from the bicarbonate
solution with sodium hydroxide from the cathode electrolyte.

18. The system of claim 14, further comprising a precipitator operably
connected to the contact system configured to produce a carbonate or a
combination of the carbonate and bicarbonate product from the bicarbonate
solution.

19. The system of claim 18, wherein the carbonate product is a
cementitious composition.

20. The system of claim 14, wherein the anode is a gas diffusion
electrode.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application
No. 61/433,641, filed Jan. 18, 2011, which is incorporated herein by
reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] In many chemical processes an alkaline solution is required to
achieve a chemical reaction, e.g., to neutralize an acid, or buffer the
pH of a solution, or precipitate an insoluble hydroxide and/or carbonate
and/or bicarbonate from a solution. One method by which the alkaline
solution may be produced is by an electrochemical system. In producing an
alkaline solution electrochemically, a large amount of energy, salt and
water may be used. Consequently, lowering the energy and material used in
the electrochemical process may be desired.

SUMMARY OF THE INVENTION

[0003] In one aspect, there is provided a method including contacting an
anode with an anode electrolyte, contacting a cathode with a cathode
electrolyte, contacting a bicarbonate solution with the cathode
electrolyte, and applying a voltage across the anode and the cathode. In
some embodiments, the method further includes producing the bicarbonate
solution. In some embodiments, the bicarbonate solution is produced from
subterranean brine. In some embodiments, the subterranean brine includes,
but not limited to, bicarbonate brine, carbonate brine, alkaline brine,
and combination thereof. In some embodiments, the bicarbonate solution is
produced from an evaporite including bicarbonate, carbonate, or
combination thereof. In some embodiments, the bicarbonate solution is
further produced by mixing bicarbonate ions in freshwater, brine, or
brackish water. In some embodiments, the bicarbonate solution is produced
by contacting carbon dioxide with a carbonate brine. In some embodiments,
the carbonate brine comprises trona brine. In some embodiments, the
bicarbonate solution is produced by dissolving carbon dioxide into an
alkaline brine. In some embodiments, the bicarbonate solution is produced
by contacting the carbon dioxide with the alkaline brine in presence of a
natural base. In some embodiments, the carbon dioxide is an industrial
waste stream including, but not limited to, flue gas from combustion; a
flue gas from a chemical processing plant; a flue gas from a plant that
produces CO2 as a byproduct; or combination thereof. In some
embodiments, the natural base includes, but not limited to, mineral,
microorganism, waste stream, coal ash, and combination thereof. In some
embodiments, the bicarbonate solution is naturally occurring bicarbonate
brine. In some embodiments, the bicarbonate solution is produced by
reacting bicarbonate hard brine with sodium carbonate and separating out
a carbonate precipitate from the bicarbonate hard brine.

[0004] In some embodiments, the cathode and the cathode electrolyte are
inside a cathode chamber and the contacting of the bicarbonate solution
with the cathode electrolyte is outside the cathode chamber. In some
embodiments, the cathode and the cathode electrolyte are inside a cathode
chamber and the contacting of the bicarbonate solution with the cathode
electrolyte is inside the cathode chamber.

[0005] In some embodiments, the bicarbonate solution includes at least 1%
w/w bicarbonate. In some embodiments, the bicarbonate solution includes
between 1%-95% w/w bicarbonate.

[0006] In some embodiments, the method produces carbonate ions by
contacting the bicarbonate solution with the cathode electrolyte. In some
embodiments, the cathode electrolyte includes seawater, freshwater,
brine, brackish water, sodium hydroxide, or combination thereof. In some
embodiments, the cathode electrolyte includes less than 1% w/w divalent
cations. In some embodiments, the divalent cations include, but not
limited to, calcium, magnesium, and combination thereof. In some
embodiments, the cathode electrolyte does not include carbon dioxide gas.
In some embodiments, the anode electrolyte includes an acid. In some
embodiments, the acid is hydrochloric acid or sulfuric acid. In some
embodiments, an oxygen gas is not formed at the anode. In some
embodiments, chlorine gas is not formed at the anode.

[0007] In some embodiments, the cathode electrolyte and the anode
electrolyte are separated by an ion exchange membrane. In some
embodiments, the ion exchange membrane is an anion exchange membrane or a
cation exchange membrane.

[0008] In some embodiments, the cathode forms hydrogen gas and the
hydrogen gas is directed from the cathode to the anode.

[0009] In some embodiments, the method further includes producing
hydroxide ions at the cathode without forming a gas at the anode on
applying the voltage across the anode and the cathode. In some
embodiments, the method further includes producing hydroxide ions in the
cathode electrolyte and hydrochloric acid or sulfuric acid in the anode
electrolyte on applying the voltage across the anode and the cathode. In
some embodiments, the method further includes producing carbonate in the
cathode electrolyte by contacting the bicarbonate solution with the
hydroxide ions in the cathode electrolyte.

[0010] In some embodiments, the voltage is between 0.05-1V across the
anode and the cathode.

[0011] In some embodiments, the method further includes producing a pH
difference of at least 4 pH units between the anode electrolyte and the
cathode electrolyte. In some embodiments, the method further includes
producing a pH difference of between 4-12 pH units between the anode
electrolyte and the cathode electrolyte when a voltage of 0.05-1V is
applied between the anode and the cathode.

[0012] In some embodiments, the method further includes treating
bicarbonate and/or carbonate ions produced by contacting the bicarbonate
solution with the cathode electrolyte with a divalent cation including,
but not limited to, calcium, magnesium, and combination thereof. In some
embodiments, the cathode and the cathode electrolyte are inside a cathode
chamber and the anode and the anode electrolyte are inside an anode
chamber. In some embodiments, the method further includes treating
bicarbonate and/or carbonate ions with a divalent cation including, but
not limited to, calcium, magnesium, and combination thereof wherein the
treatment is outside the cathode chamber. In some embodiments, the method
further includes treating bicarbonate and/or carbonate ions with a
divalent cation including, but not limited to, calcium, magnesium, and
combination thereof wherein the treatment is inside the cathode chamber.

[0013] In some embodiments, the method further includes disposing a third
electrolyte between the anode electrolyte and the cathode electrolyte. In
some embodiments, the third electrolyte is separated from the anode
electrolyte by an anion exchange membrane. In some embodiments, the anion
exchange membrane is permeable to chloride ions. In some embodiments, the
third electrolyte is separated from the cathode electrolyte by a cation
exchange membrane. In some embodiments, the cation exchange membrane is
permeable to sodium ions. In some embodiments, the third electrolyte
comprises sodium chloride.

[0014] In some embodiments, the method further includes migrating chloride
ions to the anode electrolyte from the third electrolyte and migrating
sodium ions to the cathode electrolyte from the third electrolyte upon
application of the voltage between the anode and the cathode.

[0015] In some embodiments, the anode is a gas diffusion electrode.

[0016] In another aspect, there is provided a method including producing a
bicarbonate solution from a subterranean brine, subsurface brine, or
surface brine and treating the bicarbonate solution with an alkaline
solution to produce a composition including carbonate or a combination of
bicarbonate or carbonate. In some embodiments, the alkaline solution is a
hydroxide obtained from an electrochemical cell. In some embodiments, the
subterranean brine, subsurface brine, or surface brine includes, but not
limited to, bicarbonate brine, carbonate brine, alkaline brine, and
combination thereof.

[0017] In another aspect, there is provided a method including producing a
bicarbonate solution from an evaporite and treating the bicarbonate
solution with an alkaline solution to produce a composition including
carbonate or a combination of bicarbonate or carbonate. In some
embodiments, the evaporite is trona. In some embodiments, the alkaline
solution is hydroxide obtained from an electrochemical cell.

[0018] In another aspect, there is provided a method including producing a
bicarbonate solution by contacting carbon dioxide with a carbonate brine
and treating the bicarbonate solution with an alkaline solution to
produce a composition including carbonate or a combination of bicarbonate
or carbonate. In some embodiments, the carbonate brine is trona. In some
embodiments, the carbon dioxide is an industrial waste stream including,
but not limited to, flue gas from combustion; a flue gas from a chemical
processing plant; a flue gas from a plant that produces CO2 as a
byproduct; or combination thereof. In some embodiments, the alkaline
solution is hydroxide obtained from an electrochemical cell.

[0019] In another aspect, there is provided a method including producing a
bicarbonate solution by contacting carbon dioxide with an alkaline brine
and treating the bicarbonate solution with an alkaline solution to
produce a composition including carbonate or a combination of bicarbonate
or carbonate. In some embodiments, the alkaline solution is hydroxide
obtained from an electrochemical cell. In some embodiments, the carbon
dioxide is an industrial waste stream including, but not limited to, flue
gas from combustion; a flue gas from a chemical processing plant; a flue
gas from a plant that produces CO2 as a byproduct; or combination
thereof.

[0020] In another aspect, there is provided a method including reacting
bicarbonate hard brine with sodium carbonate to form a carbonate
precipitate; separating the carbonate precipitate from the bicarbonate
hard brine to give a bicarbonate solution; and treating the bicarbonate
solution with an alkaline solution to produce a composition including
carbonate or a combination of bicarbonate or carbonate. In some
embodiments, the alkaline solution is hydroxide obtained from an
electrochemical cell.

[0021] In another aspect, there is provided a method including contacting
bicarbonate solution derived from one or more of natural substances with
an alkaline solution to produce a product including carbonate or mixture
of carbonate and bicarbonate.

[0022] In some embodiments, the product is a cement composition.

[0023] In some embodiments, the one or more of natural substances include,
but are not limited to, naturally occurring brines including
subterranean, subsurface and surface brines, crystalline shoreline or
bottom crusts, shallow lake bottom crusts, surface efflorescence,
minerals, solutions obtained after the mining of the ores, evaporite, and
lakes.

[0024] In another aspect, there is provided a system including an anode
electrolyte in contact with an anode; a cathode electrolyte in contact
with a cathode; and a contact system operably connected to the cathode
electrolyte configured to contact a bicarbonate solution with the cathode
electrolyte. In another aspect, there is provided a system including a
reactor system configured to produce a bicarbonate solution; a contact
system operably connected to the reactor system configured to contact the
bicarbonate solution with an alkaline solution; and a precipitator
operably connected to the contact system configured to produce a
carbonate or a combination of the carbonate and bicarbonate product from
the bicarbonate solution.

[0025] In some embodiments, the system further includes a reactor system
operably connected to the contact system configured to produce the
bicarbonate solution. In some embodiments, the reactor system comprises a
contactor configured to contact carbon dioxide with a carbonate brine to
produce a bicarbonate solution.

[0026] In some embodiments, the cathode and the cathode electrolyte are
inside a cathode chamber and the contact system is outside the cathode
chamber. In some embodiments, the cathode and the cathode electrolyte are
inside a cathode chamber and the contact system is inside the cathode
chamber.

[0027] In some embodiments, the cathode electrolyte and the anode
electrolyte are separated by an ion exchange membrane. In some
embodiments, the ion exchange membrane is an anion exchange membrane or a
cation exchange membrane. In some embodiments, the system is configured
to direct hydrogen gas from the cathode to the anode. In some
embodiments, the system comprises a duct that directs the hydrogen gas
from the cathode to the anode.

[0028] In some embodiments, the system is configured to produce hydroxide
ions at the cathode without forming a gas at the anode on applying a
voltage across the anode and the cathode. In some embodiments, the system
is configured to produce hydroxide ions in the cathode electrolyte and an
acid in the anode electrolyte on applying a voltage across the anode and
the cathode.

[0029] In some embodiments, the system further includes a device to apply
a voltage across the anode and the cathode. In some embodiments, the
voltage is between 0.05-1.5V.

[0030] In some embodiments, the system is configured to produce a pH
difference of at least 4 pH units between the anode electrolyte and the
cathode electrolyte. In some embodiments, the system is configured to
produce a pH difference of between 4-12 pH units between the anode
electrolyte and the cathode electrolyte when a voltage of 0.05-1V is
applied between the anode and the cathode.

[0031] In some embodiments, the system is configured to produce carbonate
ions by a reaction of the bicarbonate ions from the bicarbonate solution
with sodium hydroxide from the cathode electrolyte.

[0032] In some embodiments, the system is configured to treat bicarbonate
and/or carbonate ions with a divalent cation including, but not limited
to, calcium, magnesium, and combination thereof.

[0033] In some embodiments, the system is a continuous flow operation.

[0034] In some embodiments, the contact system configured to contact the
bicarbonate solution to the cathode electrolyte includes a duct that
directs the bicarbonate solution to the cathode electrolyte.

[0035] In some embodiments, the system includes a third electrolyte
disposed between the anode electrolyte and the cathode electrolyte. In
some embodiments, the third electrolyte is separated from the anode
electrolyte by an anion exchange membrane. In some embodiments, the anion
exchange membrane is permeable to chloride ions. In some embodiments, the
third electrolyte is separated from the cathode electrolyte by a cation
exchange membrane. In some embodiments, the cation exchange membrane is
permeable to sodium ions. In some embodiments, the third electrolyte
includes sodium chloride.

[0036] In some embodiments, the system is configured to cause a migration
of chloride ions to the anode electrolyte from the third electrolyte and
to cause a migration of sodium ions to the cathode electrolyte from the
third electrolyte upon application of a voltage between the anode and the
cathode.

[0037] In some embodiments, the anode is a gas diffusion electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following drawings illustrate by way of examples and not by
limitation some embodiments of the present system and method.

[0041] FIGS. 2A and 2B are an illustration of an embodiment of the
invention.

[0042] FIGS. 3A and 3B are an illustration of an embodiment of the
invention.

[0043] FIGS. 4A and 4B are an illustration of an embodiment of the
invention.

[0044] FIGS. 5A and 5B are an illustration of an embodiment of the
invention.

[0045] FIG. 6 is an illustration of an embodiment of the invention.

[0046] FIG. 7 is flow chart of an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0047] There are provided systems and methods for contacting a bicarbonate
solution with an alkaline solution to produce carbonate and/or
bicarbonate compositions. The bicarbonate solution may be derived from
any natural substance. Various methods to produce bicarbonate solution
are as described herein. In some embodiments, the alkaline solution is
produced in an electrochemical cell. The electrochemical cell can be any
electrochemical cell known in the art that produces an alkaline solution.
Typically, an electrochemical cell comprises a cathode chamber comprising
a cathode electrolyte and a cathode and an anode chamber comprising an
anode electrolyte and an anode. As disclosed herein, on applying a
voltage across the anode and the cathode, cations, e.g., sodium ions
migrate to the cathode to produce an alkaline solution such as, sodium
hydroxide. In some embodiments, upon reaction of the sodium hydroxide
with the bicarbonate solution inside the cathode chamber or outside the
cathode chamber, sodium carbonate and/or mixture of sodium carbonate and
sodium bicarbonate is formed. In some embodiments, the electrochemical
cell produces an alkaline solution in the cathode chamber and an acid,
such as a hydrochloric acid or sulfuric acid in the anode chamber.
Further, as described herein, hydrogen gas and hydroxide ions may be
produced at the cathode, and in some embodiments, some or all of the
hydrogen gas produced at the cathode may be directed to the anode where
it may be oxidized to produce hydrogen ions. The anions in the anode
electrolyte, e.g., chloride ions react with the hydrogen ions migrated
from the anode to produce an acid, e.g., hydrochloric acid, sulfuric
acid, etc. in the anode electrolyte. In some embodiments, a salt solution
comprising, e.g., sodium chloride or sodium sulfate, is used as the anode
electrolyte or the cathode electrolyte to produce the alkaline solution.
In some embodiments, such salt solution is brine. The carbonate
compositions produced by treating the bicarbonate solution with the
hydroxide may be used to make cementitious compositions.

[0048] The methods and systems provided herein show surprising and
unexpected results as the amount of alkaline solution required to convert
the bicarbonate solution to the carbonate ions is less than the amount of
alkaline solution required to convert carbonic acid to the carbonate
ions, thereby reducing the energy consumption of the process. For
example, the amount of alkaline solution required to remove one proton
from the bicarbonate ion to form the carbonate ion is less than the
amount of alkaline solution required to remove two protons from the
carbonic acid to form the carbonate ion. Further, in some embodiments,
the addition of the bicarbonate solution to the cathode electrolyte may
reduce the pH of the cathode electrolyte thereby reducing the overall
cell potential and the energy consumption of the process. Further, the
acid produced can be utilized in various ways including dissolving
materials, e.g., minerals and biomass.

[0049] Typically, Ordinary Portland Cement (OPC) is made primarily from
limestone, certain clay minerals, and gypsum, in a high temperature
process that drives off carbon dioxide and chemically combines the
primary ingredients into new compounds. The energy required to fire the
mixture consumes about 4 GJ per ton of cement produced. Because the
carbon dioxide is generated by both the cement production process itself,
as well as by energy plants that generate power to run the production
process, cement production is a leading source of current carbon dioxide
atmospheric emissions. In addition to the pollution problems associated
with Portland cement production, the structures produced with Portland
cements may have a repair and maintenance expense because of the
instability of the cured product produced from Portland cement.

[0050] The methods and systems provided herein reduce the carbon foot
print by using the bicarbonate solution to make the carbonate
compositions. In some embodiments, the production of such compositions
may not require an energy intensive process and thereby reduce the carbon
dioxide atmospheric emissions. In some embodiments, the production of
cement products from the compositions, as described herein, may not emit
as much carbon dioxide or may not emit carbon dioxide at all, as is
emitted by Portland cement and thereby reduce the overall carbon dioxide
atmospheric emissions. In still further embodiments, the cement
compositions provided herein may partially or completely replace the
carbon emitting cements, such as OPC thereby reducing the carbon dioxide
atmospheric emissions and the carbon foot print. The compositions
provided herein may be mixed with OPC to give the cement material with
equal or higher strength, thereby reducing the amount of OPC to make
cement.

[0051] As can be appreciated by one ordinarily skilled in the art, since
the present system and method can be configured with an alternative,
equivalent salt solution, e.g., a potassium sulfate solution or a sodium
sulfate solution, to produce an equivalent alkaline solution, e.g.,
potassium hydroxide and/or potassium carbonate and/or potassium
bicarbonate or sodium hydroxide and/or sodium carbonate and/or sodium
bicarbonate in the cathode electrolyte, and an equivalent acid, e.g.,
sulfuric acid in the anode electrolyte, by applying the voltage as
disclosed herein across the anode and cathode. The invention is not
limited to the exemplary embodiments described herein, but is adaptable
for use with an equivalent salt solution, e.g., potassium sulfate or
sodium sulfate, to produce an alkaline solution in the cathode
electrolyte and an acid, e.g., sulfuric acid in the anode electrolyte.
Accordingly, to the extent that such equivalents are based on or
suggested by the present system and method, these equivalents are within
the scope of the appended claims.

[0052] Before the present invention is described in greater detail, it is
to be understood that this invention is not limited to particular
embodiments described, as such may, of course, vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to be
limiting, since the scope of the present invention will be limited only
by the appended claims.

[0053] Where a range of values is provided, it is understood that each
intervening value, to the tenth of the unit of the lower limit unless the
context clearly dictates otherwise, between the upper and lower limit of
that range and any other stated or intervening value in that stated
range, is encompassed within the invention. The upper and lower limits of
these smaller ranges may independently be included in the smaller ranges
and are also encompassed within the invention, subject to any
specifically excluded limit in the stated range. Where the stated range
includes one or both of the limits, ranges excluding either or both of
those included limits are also included in the invention.

[0054] Certain ranges are presented herein with numerical values being
preceded by the term "about." The term "about" is used herein to provide
literal support for the exact number that it precedes, as well as a
number that is near to or approximately the number that the term
precedes. In determining whether a number is near to or approximately a
specifically recited number, the near or approximating unrequited number
may be a number, which, in the context in which it is presented, provides
the substantial equivalent of the specifically recited number.

[0055] Unless defined otherwise, all technical and scientific terms used
herein have the same meaning as commonly understood by one of ordinary
skill in the art to which this invention belongs. Although any methods
and materials similar or equivalent to those described herein can also be
used in the practice or testing of the present invention, representative
illustrative methods and materials are now described.

[0056] All publications and patents cited in this specification are herein
incorporated by reference as if each individual publication or patent
were specifically and individually indicated to be incorporated by
reference and are incorporated herein by reference to disclose and
describe the methods and/or materials in connection with which the
publications are cited. The citation of any publication is for its
disclosure prior to the filing date and should not be construed as an
admission that the present invention is not entitled to antedate such
publication by virtue of prior invention. Further, the dates of
publication provided may be different from the actual publication dates
which may need to be independently confirmed.

[0057] It is noted that, as used herein and in the appended claims, the
singular forms "a," "an," and "the" include plural references unless the
context clearly dictates otherwise. It is further noted that the claims
may be drafted to exclude any optional element. As such, this statement
is intended to serve as antecedent basis for use of such exclusive
terminology as "solely," "only" and the like in connection with the
recitation of claim elements, or use of a "negative" limitation.

[0058] As will be apparent to those of skill in the art upon reading this
disclosure, each of the individual embodiments described and illustrated
herein has discrete components and features which may be readily
separated from or combined with the features of any of the other several
embodiments without departing from the scope or spirit of the present
invention. Any recited method can be carried out in the order of events
recited or in any other order which is logically possible.

A. Methods and Systems of Bicarbonate Solution

[0059] In one aspect, there is provided a method to contact bicarbonate
solution with an alkaline solution to produce a product comprising
carbonate or mixture of carbonate and bicarbonate. In some embodiments,
the bicarbonate solution is derived from one or more natural substances.
Accordingly, there is provided a method to contact bicarbonate solution
derived from one or more of natural substances with an alkaline solution
to produce a product comprising carbonate or mixture of carbonate and
bicarbonate. As illustrated in FIG. 1A, the methods and systems provided
herein include contacting the bicarbonate solution with an alkaline
solution to produce carbonate or carbonate and bicarbonate solution or
product. The systems provided herein are suitable for all the methods of
the invention.

[0060] As used herein, the "bicarbonate solution" includes any bicarbonate
solution derived from one or more natural substances. Examples of natural
substances include, without limitation, naturally occurring brines
including subterranean, subsurface and surface brines, crystalline
shoreline or bottom crusts, shallow lake bottom crusts, surface
efflorescence, minerals, solutions obtained after the mining of the ores,
evaporite, and lakes. In some embodiments, the bicarbonate solution is
derived from a naturally occurring brine, e.g., subterranean brine,
subsurface brine, surface brine, or naturally occurring lake. In some
embodiments, the bicarbonate solution is made from minerals where the
minerals are crushed and dissolved in brine and optionally further
processed. The minerals can be found under the surface, on the surface,
or subsurface of the lakes. The bicarbonate solution can also be made
from an evaporite. The bicarbonate solution may include other oxyanions
of carbon in addition to bicarbonate (HCO3-), such as, but not
limited to, carbonic acid (H2CO3) and/or carbonate
(CO32).

[0061] As used herein, the "alkaline solution" is any solution that
possesses sufficient alkalinity or basicity to remove one or more protons
from a proton-containing species in solution. The alkaline solution may
be a synthetic or a naturally occurring base. Examples of base include,
but not limited to, hydroxides, such as calcium hydroxide, sodium
hydroxide, potassium hydroxide etc. In some embodiments, the base is
obtained by an electrochemical process. Some examples of the
electrochemical process are described herein. In some embodiments, the
base is a naturally occurring base, mineral, microorganism, waste stream,
coal ash, and combination thereof. Examples of the alkaline solution that
may be used in the methods and systems of the invention include, but not
limited to, organic bases, such as, formate, acetate, propionate,
butyrate, and valerate, among others; and bacteria, among others.
Examples of such microorganisms are fungi that produce alkaline protease
(e.g., the deep-sea fungus Aspergillus ustus with an optimal pH of 9) and
bacteria that create alkaline molecules (e.g., cyanobacteria such as
Lyngbya sp. from the Atlin wetland in British Columbia, which increases
pH from a byproduct of photosynthesis). In some embodiments, organisms
are used to produce alkalinity, wherein the organisms (e.g., Bacillus
pasteurii, which hydrolyzes urea to ammonia) metabolize a contaminant
(e.g. urea) to produce alkaline solutions (e.g., ammonia, ammonium
hydroxide). In addition, waste streams from various industrial processes
may provide alkalinity. Such waste streams include, but are not limited
to, mining wastes; fossil fuel burning ash (e.g., combustion ash such as
fly ash, bottom ash, boiler slag); slag (e.g. iron slag, phosphorous
slag); cement kiln waste; oil refinery/petrochemical refinery waste (e.g.
oil field and methane seam brines); coal seam wastes (e.g. gas production
brines and coal seam brine); paper processing waste; water softening
waste brine (e.g., ion exchange effluent); silicon processing wastes;
agricultural waste; metal finishing waste; high pH textile waste; and
caustic sludge.

[0062] In some embodiments, the systems and methods provided herein
include systems and methods to produce the bicarbonate solution. After
the production of the bicarbonate solution by the methods and systems
described herein, the bicarbonate solution may be contacted with the
alkaline solution, such as, the cathode electrolyte, as described herein.
The systems and methods to produce the bicarbonate solution, to
optionally modify the bicarbonate solution and/or to store the
bicarbonate solution, are as further described herein.

[0063] In some embodiments, the bicarbonate solution is derived from a
subterranean brine. The subterranean brine that is employed in
embodiments of the invention may be from any convenient subterranean
brine source. "Subterranean brine" is employed in its conventional sense
to include naturally occurring or anthropogenic saline compositions
obtained from a geological location. The geological location of the
subterranean brine may be found below ground (subterranean geological
location). Examples of subterranean, subsurface and surface brines
include, but not limited to, bicarbonate brine, carbonate brine, alkaline
brine, and hard brine, such as, but not limited to, alkaline hard brine,
carbonate hard brine, bicarbonate hard brine, or mixture thereof.
Subterranean brines of the invention may be subterranean saline
compositions and in some embodiments, may have circulated through crystal
rocks and become enriched in substances leaching from the surrounding
mineral. Saline composition includes an aqueous solution which has a
salinity of 500 ppm total dissolved solids (TDS) or greater, 1,000 ppm
total dissolved solids (TDS) or greater, 5,000 ppm total dissolved solids
(TDS) or greater, 10,000 ppm total dissolved solids (TDS) or greater,
such as 20,000 ppm TDS or greater and including 50,000 ppm TDS or greater
or between 5,000 ppm to 100,000 ppm. Subterranean geological location
includes a geological location which is located below ground level. The
ground level includes a solid-fluid interface of the earth's surface,
such as a solid-gas interface as found on dry land where dry land meets
the earth's atmosphere, as well as a liquid-solid interface as found
beneath a body of surface water (e.g., lack, ocean, stream, etc) where
solid ground meets the body of water (where examples of this interface
include lake beds, ocean floors, etc). As such, the subterranean location
can be a location beneath land or a location beneath a body of water
(e.g., oceanic ridge). For example, a subterranean location may be a deep
geological aquifer or an underground well located in the sedimentary
basins of a petroleum field, a subterranean metal ore, a geothermal
field, or an oceanic ridge, among other underground locations.

[0064] In some embodiments, single brine may be employed or a mixture of
two or more brines may be employed to produce the bicarbonate solution
for the methods of the invention. A single brine includes a brine which
has been obtained from a single, distinct geological location (e.g.,
underground well or a naturally occurring lake or deposit). A mixture of
two or more brines includes mixing of two or more brines, where each
brine is obtained from a distinct geological location or is a mixture of
a synthetic brine (obtained by dissolving bicarbonate ions in fresh water
or saline water) and a naturally occurring brine.

[0065] The subterranean geological location may be a location that is 100
m or deeper below ground level, or 200 m or deeper below ground level, or
300 m or deeper below ground level, or 400 m or deeper below ground
level, or 500 m or deeper below ground level, or 600 m or deeper below
ground level, or 700 m or deeper below ground level, or 800 m or deeper
below ground level, or 900 m or deeper below ground level, or 1000 m or
deeper below ground level, including 1500 m or deeper below ground level,
2000 m or deeper below ground level, 2500 m or deeper below ground level
and 3000 m or deeper below ground level. In some embodiments, a
subterranean location is a location that is between 100 m and 3500 m
below ground level, such as between 200 m and 2500 m below ground level,
such as between 200 m and 2000 m below ground level, such as between 200
m and 1500 m below ground level, such as between 200 m and 1000 m below
ground level and including between 200 m and 800 m below ground level.
Subterranean brines of the invention may include, but are not limited to,
oil-field brines, basinal brines, basinal water, pore water, formation
water, and deep sea hypersaline waters, among others.

[0066] In some embodiments of the methods and systems provided herein, the
bicarbonate solution may contain bicarbonate in a concentration of 25 ppm
or more; or 50 ppm or more; or 100 ppm or more; or 200 ppm or more; or
300 ppm or more; or 500 ppm or more; or 800 ppm or more; or 1000 ppm or
more; or 1500 ppm or more; or 2000 ppm or more; or 3000 ppm or more; or
5000 ppm or more; or 8000 ppm or more; or 10,000 ppm or more; or 20,000
ppm or more; or 40,000 ppm or more; or 50,000 ppm or more; or 80,000 ppm
or more; or 100,000 ppm or more; or 500,000 ppm or more; or 1,000,000 ppm
or more; or between 25-1,000,000 ppm; or between 25-500,000 ppm; or
between 25-100,000 ppm; or between 25-80,000 ppm; or between 25-50,000
ppm; or between 25-10,000 ppm; or between 25-5,000 ppm; or between
25-1,000 ppm; or between 25-500 ppm; or between 25-100 ppm; or between
50-1,000,000 ppm; or between 50-500,000 ppm; or between 50-100,000 ppm;
or between 50-80,000 ppm; or between 50-50,000 ppm; or between 50-10,000
ppm; or between 50-5,000 ppm; or between 50-1,000 ppm; or between 50-500
ppm; or between 50-100 ppm; or between 100-1,000,000 ppm; or between
100-500,000 ppm; or between 100-100,000 ppm; or between 100-80,000 ppm;
or between 100-50,000 ppm; or between 100-10,000 ppm; or between
100-5,000 ppm; or between 100-1,000 ppm; or between 100-500 ppm; or
between 500-1,000,000 ppm; or between 500-500,000 ppm; or between
500-100,000 ppm; or between 500-80,000 ppm; or between 500-50,000 ppm; or
between 500-10,000 ppm; or between 500-5,000 ppm; or between 500-1,000
ppm; or between 1000-1,000,000 ppm; or between 1000-500,000 ppm; or
between 1000-100,000 ppm; or between 1000-80,000 ppm; or between
1000-50,000 ppm; or between 1000-10,000 ppm; or between 1000-5,000 ppm;
or between 5000-1,000,000 ppm; or between 5000-500,000 ppm; or between
5000-100,000 ppm; or between 5000-80,000 ppm; or between 5000-50,000 ppm;
or between 5000-10,000 ppm; or between 10,000-1,000,000 ppm; or between
10,000-500,000 ppm; or between 10,000-100,000 ppm; or between
10,000-80,000 ppm; or between 10,000-50,000 ppm; or between
50,000-1,000,000 ppm; or between 50,000-500,000 ppm; or between
50,000-100,000 ppm; or between 50,000-80,000 ppm; or between
100,000-1,000,000 ppm or between 100,000-500,000 ppm; or between
500,000-1,000,000 ppm.

[0067] In some embodiments of the methods and systems provided herein, the
bicarbonate solution includes bicarbonate in a concentration of at least
1% w/w; or at least 2% w/w; or at least 3% w/w; or at least 4% w/w; or at
least 5% w/w; or at least 6% w/w; or at least 8% w/w; or at least 10%
w/w; or at least 20% w/w; or at least 30% w/w; or at least 40% w/w; or at
least 50% w/w; or at least 75% w/w; or at least 90% w/w; or between
0.1%-95% w/w; or between 0.1%-90% w/w; or between 0.1%-80% w/w; or
between 0.1%-70% w/w; or between 0.1%-60% w/w; or between 0.1%-50% w/w;
or between 0.1%-40% w/w; or between 0.1%-30% w/w; or between 0.1%-20%
w/w; or between 0.1%-10% w/w; or between 0.1%-5% w/w; or between 0.1%-3%
w/w; or between 0.1%-2% w/w; or between 0.5%-95% w/w; or between 0.5%-90%
w/w; or between 0.5%-80% w/w; or between 0.5%-70% w/w; or between
0.5%-60% w/w; or between 0.5%-50% w/w; or between 0.5%-40% w/w; or
between 0.5%-30% w/w; or between 0.5%-20% w/w; or between 0.5%-10% w/w;
or between 0.5%-5% w/w; or between 0.5%-3% w/w; or between 0.5%-2% w/w;
or between 1%-95% w/w; or between 1%-90% w/w; or between 1%-80% w/w; or
between 1%-70% w/w; or between 1%-60% w/w; or between 1%-50% w/w; or
between 1%-40% w/w; or between 1%-30% w/w; or between 1%-20% w/w; or
between 1%-10% w/w; or between 1%-5% w/w; or between 1%-3% w/w; or
between 1%-2% w/w; or between 2%-95% w/w; or between 2%-90% w/w; or
between 2%-80% w/w; or between 2%-70% w/w; or between 2%-60% w/w; or
between 2%-50% w/w; or between 2%-40% w/w; or between 2%-30% w/w; or
between 2%-20% w/w; or between 2%-10% w/w; or between 2%-5% w/w; or
between 2%-3% w/w; or between 3%-95% w/w; or between 3%-90% w/w; or
between 3%-80% w/w; or between 3%-70% w/w; or between 3%-60% w/w; or
between 3%-50% w/w; or between 3%-40% w/w; or between 3%-30% w/w; or
between 3%-20% w/w; or between 3%-10% w/w; or between 3%-5% w/w; or
between 4%-95% w/w; or between 4%-90% w/w; or between 4%-80% w/w; or
between 4%-70% w/w; or between 4%-60% w/w; or between 4%-50% w/w; or
between 4%-40% w/w; or between 4%-30% w/w; or between 4%-20% w/w; or
between 4%-10% w/w; or between 4%-5% w/w; or between 5%-95% w/w; or
between 5%-90% w/w; or between 5%-80% w/w; or between 5%-70% w/w; or
between 5%-60% w/w; or between 5%-50% w/w; or between 5%-40% w/w; or
between 5%-30% w/w; or between 5%-20% w/w; or between 5%-10% w/w; or
between 10%-95% w/w; or between 10%-90% w/w; or between 10%-80% w/w; or
between 10%-70% w/w; or between 10%-60% w/w; or between 10%-50% w/w; or
between 10%-40% w/w; or between 10%-30% w/w; or between 10%-20% w/w; or
between 20%-95% w/w; or between 20%-90% w/w; or between 20%-80% w/w; or
between 20%-70% w/w; or between 20%-60% w/w; or between 20%-50% w/w; or
between 20%-40% w/w; or between 20%-30% w/w; or between 30%-95% w/w; or
between 30%-90% w/w; or between 30%-80% w/w; or between 30%-70% w/w; or
between 30%-60% w/w; or between 30%-50% w/w; or between 30%-40% w/w; or
between 40%-95% w/w; or between 40%-90% w/w; or between 40%-80% w/w; or
between 40%-70% w/w; or between 40%-60% w/w; or between 40%-50% w/w; or
between 50%-95% w/w; or between 50%-90% w/w; or between 50%-80% w/w; or
between 50%-70% w/w; or between 50%-60% w/w; or between 60%-95% w/w; or
between 60%-90% w/w; or between 60%-80% w/w; or between 60%-70% w/w; or
between 70%-95% w/w; or between 70%-90% w/w; or between 70%-80% w/w; or
between 80%-95% w/w; or between 80%-90% w/w; or between 90%-95% w/w; or
1% w/w; or 2% w/w; or 3% w/w; or 4% w/w; or 5% w/w; or 6% w/w; or 8% w/w;
or 10% w/w; or 20% w/w; or 30% w/w; or 40% w/w; or 50% w/w; or 75% w/w;
or 90% w/w.

[0068] The concentration recited herein may also be in w/v or v/v ratios.

[0069] In some embodiments, the amount of bicarbonate recited above is
present in the subterranean brine. In some embodiments, the amount of
bicarbonate recited above is present in the ore above ground. In some
embodiments, the amount of bicarbonate recited above is present in the
underground ore. In some embodiments, the amount of bicarbonate recited
above is present in the brine extracted from the ore to form the
bicarbonate solution. In some embodiments, the amount of bicarbonate
recited above is present in the brine after the processing of the ore.
Some of the examples of the methods of processing are as described
herein. In some embodiments, the amount of bicarbonate recited above is
present in the bicarbonate solution produced in accordance with the
embodiments of the invention. In some embodiments, the amount of
bicarbonate recited above is present in the bicarbonate solution that is
contacted with the alkaline solution, such as, cathode electrolyte.

[0070] Deposits of sodium carbonate/bicarbonate may be found in countries
like United States, China, Botswana, Uganda, Kenya, Mexico, Peru, India,
Egypt, South Africa and Turkey. It may be found both as extensive beds of
sodium minerals and as sodium-rich waters (brines). The bicarbonate
brines may include carbonate ions such that they may be called carbonate
brines. Such carbonate brines have been described in U.S. Provisional
Patent Application No. 61/371,620, filed 6 Aug. 2010, titled "Calcium
carbonate compositions and methods thereof," which is incorporated herein
by reference in its entirety.

[0071] The origin of sodium carbonate and/or sodium bicarbonate in natural
deposits can be due to various reasons, including (a) evaporation of
sodium carbonate and/or sodium bicarbonate-rich thermal spring water; (b)
carbonation of sodium sulfide to sodium carbonate and/or sodium
bicarbonate; (c) ion-exchange in sodium bearing soils; (d) concentration
dependent and temperature dependent equilibrium relationships among
carbon dioxide and carbonate that converts carbonate solutions to sodium
bicarbonate, or carbon dioxide removed from sodium bicarbonate solutions
to form carbonates; and (e) leaching of alkaline carbonatites or basic
ultra-basics rocks. The sodium may have been derived from the leaching of
sodic feldspars or volcanic ash deposits, and the carbon dioxide may have
been derived from the atmosphere. The groundwaters in metamorphic or
igneous terrains produce alkaline solutions on evaporation. The absence
of chloride and sulfate in these rocks permits solutions to become
predominantly sodium and carbon dioxide bearing. The chemical
fractionation of inflowing waters and brines within closed depositional
basins can produce different minerals accumulating in separate areas.

[0072] Some types of carbonate and/or sodium bicarbonate bearing minerals
that can be used to make bicarbonate brines are illustrated in Table I.

[0073] It is to be understood that the carbonate and/or bicarbonate
bearing minerals illustrated in Table I are for illustrative purposes
only and that other carbonate and/or bicarbonate bearing minerals known
in the art, are well within the scope of the invention. The carbonate
and/or bicarbonate minerals illustrated in Table I may be present in
separate deposits or may be present in the same deposit. Carbonate and/or
bicarbonate brines useful to produce the bicarbonate solution used in the
methods and systems of the invention, can be obtained from, for example,
trona deposits located in Utah, California (such as, Searles Lake and
Owens Lake); Green river formation in Wyoming; Colorado; and Railroad
valley in Nevada; shallow-water limestones and dolostones of the
Conococheague Limestone (Upper Cambrian) of western Maryland; lakes
located in East African Rift Valley (e.g., Lake Bogoria, Lake Natron and
Lake Magadi); lake Chad basin in Africa; lakes located in Libyan Desert
in Egypt (Wadi Natrun system); and lakes located in central Asia (from
south-east Siberia to north-east China) such as, Wucheng basin and Biyang
basin in Henan province of China; Sambhar lake and Lonar lake in India;
and Zabuye Caka, Bangkog Cuo, and Guogaling Cuo in Tibet. The carbonate
and/or bicarbonate minerals include, but are not limited to, trona, minor
nahcolite, and trace amounts of pirssonite and thermonatrite.

[0075] Trona and dolomite are associated throughout the trona zone.
Calcite, zeolites, feldspar, and clay minerals are the typical minerals
found within the associated rocks of the trona deposit. The trona
crystals, which are generally white and/or gray due to impurities, occur
in massive units and as disseminated crystals in claystone and shale.
Crude trona ("trona ore") may comprise 80-95% of sodium sesquicarbonate
(Na2CO3.NaHCO3.2H2O) and, in lesser amounts, sodium
chloride (NaCl), sodium sulfate (Na2SO4), organic matter, and
insolubles such as clay and shales. In Wyoming, these deposits are
located in 25 separate identified beds or zones ranging from 800 to 2800
feet below the earth's surface and are typically extracted by
conventional mining techniques, such as, the room and pillar and longwall
methods.

[0076] The ores may require processing in order to recover the carbonate
and/or bicarbonate brines or the bicarbonate solution. Typically, most of
the sodium carbonate from the Green River deposits is produced from the
conventionally mined trona ore via the sesquicarbonate process or the
monohydrate process. Both processes may use the same procedure but in
different sequences. The "monohydrate" process involves crushing and
screening the bulk trona ore which, as noted above, contains both sodium
carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) as well
as impurities such as silicates and organic matter. After the ore is
screened, it may be calcined (i.e., heated) at temperatures greater than
150° C. to convert sodium bicarbonate to sodium carbonate. In some
embodiments, the ore may not be calcined and the bicarbonate brine may be
prepared from the ore. The crude soda ash may be dissolved in recycled
liquor which may be then clarified and filtered to remove the insoluble
solids. The liquor may be carbon treated to remove dissolved organic
matter which may cause foaming and color problems in the final product,
and may be again filtered to remove entrained carbon before going to a
monohydrate crystallizer unit. This unit has a high temperature
evaporator system generally having one or more effects (evaporators),
where sodium carbonate monohydrate may be crystallized. The resulting
slurry may then be centrifuged, and the separated monohydrate crystals
may be sent to dryers to produce soda ash. The soluble impurities may be
recycled with the centrate to the crystallizer where they may be further
concentrated.

[0077] In some embodiments, the underground ore may be subjected to
solution mining where water is injected (or an aqueous solution) into a
deposit of soluble ore, the solution may be allowed to dissolve as much
ore as possible, and the solution may be pumped to the surface. The
solution may be evaporated to produce brines with higher alkalinity or
higher concentration of carbonate and/or bicarbonate ions. Bulk trona
(sodium sesquicarbonate), for example, may be dissolved above ground in
an aqueous solvent at high temperatures which may be difficult to achieve
underground. This may allow for a higher concentration to be achieved.
After purification, these liquors may be cooled to recrystallize the
carbonate or sesquicarbonate, which may be then calcined and converted to
soda ash.

[0078] In some embodiments, the tailings and the spent solutions, obtained
after the mining of the carbonate ores, may be used as carbonate and/or
bicarbonate brines in the systems and methods of the present invention.

[0079] In some embodiments, the carbonate and/or bicarbonate brines of the
invention are brine-bearing-evaporate or evaporite horizons in the lake.
A system of wells (injection and production) and pipelines may be used to
produce brine from the horizons. In some embodiments, an effluent may be
injected into the evaporite horizon to manufacture brine by solution
mining. In some embodiments, the carbonate and/or bicarbonate brines of
the invention are made from the evaporite deposits exposed at the
surface. For example, at Owens lake, Trona is exposed at the surface and
is selectively mined with an excavator, stockpiled adjacent to the area
of excavation, and later spread out on the surface to air dry.

[0080] Large deposits of lithium carbonate are found in Chile in Salar de
Atacama in the Andes Mountains and in Antofagasta. In the United States,
the lithium carbonate brines are in Nevada. There is also a lithium
carbonate plant in Argentina on the Salar del Hombre Muerto. Other
countries with deposits of lithium carbonate brines include China,
Russia, Australia, Canada, and Zimbabwe. In some embodiments, one or more
of the elements from the carbonate/bicarbonate brines are removed before
using the carbonate/bicarbonate brines for the systems and methods of
this invention. The one or more elements that may be removed before using
the carbonate/bicarbonate brines include, but are not limited to,
lithium, borate, iron, etc. These one or more elements may be used for
other industrial applications. For example, the lithium carbonate brines
may be pumped from the salt mine and may be evaporated in large shallow
pools, where a sequential crystallization of the salts may be started.
Since the brines of chlorides may be saturated with sodium chloride, the
first salt to be precipitated may be halite, or if sulfates are present,
halite and hydrated calcium sulfate. The precipitation may continue with
silvinite (KClNaCl) and afterward silvite (KCl). The latter may be a
product for industrial use so that toward the end of the precipitation of
the silvite, the brine may be transferred to another pool and the
precipitated salt thereof may be recovered for obtaining potassium
chloride by differential floatation. After the precipitation,
crystallization of carnalite (KClMgCl2.6H2O) and then
bishoffite (MgCl2.6H2O) may take place. In this stage, the
lithium may be increased to about 4.5-5.5%, with a magnesium content of
about 4%. At that point, lithium carnalite (LiClMgCl2.6H2O) may
get precipitated.

[0081] Other carbonate/bicarbonate brines include soda lakes, such as,
mono lake, big soda lake, and soap lake. Mono Lake is situated on the
eastern slope of the Sierra Nevada mountain range in California. It is a
saline lake (˜90 g/l) with a pH around 10. Calcium carbonate is the
principal precipitate and causes the formation of tufa towers which reach
a height of almost one meter above the water. In addition to carbonate,
mono lake also contains phosphate, sulfate and other ions, such as,
arsenic and selenium. Soap Lake is another soda lake situated in central
Washington State (USA), with increasing salinity and alkalinity.
Characteristic of this lake are its sharp stratification and its high
sulfide concentration (200 mM) in the monimolimnion, i.e., the bottom
layer of the lake. The salinity goes from 15 g/l in the mixolimnion,
i.e., the top layer of the lake, to 140 g/l in the monimolimnion and the
pH is round 10.

[0082] In one aspect, there is provide a method to produce bicarbonate
solution by the methods described herein and treat the bicarbonate
solution with an alkaline solution to produce carbonate or carbonate and
bicarbonate solution or product. In one aspect, there is provided a
system including a reactor system configured to produce bicarbonate
solution and a precipitator configured to produce a carbonate product
from the bicarbonate solution. In one aspect, there is provided a system
including a reactor system configured to produce bicarbonate solution; a
contact system configured to contact the bicarbonate solution with an
alkaline solution, and a precipitator configured to produce a carbonate
product from the bicarbonate solution. In one aspect, there is provided a
system including a contact system configured to contact the bicarbonate
solution with an alkaline solution, and a precipitator configured to
produce a carbonate product from the bicarbonate solution. In one aspect,
there is provided a system including a reactor system configured to
produce a bicarbonate solution; a contact system operably connected to
the reactor system configured to contact the bicarbonate solution with an
alkaline solution; and a precipitator operably connected to the contact
system configured to produce a carbonate or a combination of the
carbonate and bicarbonate product from the bicarbonate solution.

[0083] The reactor system may be any means suitable to produce the
bicarbonate solution from suitable reagents. The reactor may be
configured to include any number of different elements, such as gas
mixer/gas absorber, gas/liquid contactor, temperature regulators (e.g.,
configured to heat the solution to a desired temperature), chemical
additive elements, e.g., for introducing chemical pH elevating agents
(such as natural bases) into the water, etc to produce the bicarbonate
solution in accordance with the methods and systems of the invention.
This reactor may operate as a batch process or a continuous process. The
contact system and the precipitator are as described herein.

[0084] The contact system may be any means suitable to contact the
bicarbonate solution with the alkaline solution. Examples of contact
system configured to contact the bicarbonate solution with an alkaline
solution include, but not limited to, duct, pipe, tank, or a conduit, or
the like that directs the bicarbonate solution to the alkaline solution
or vice versa. The contact system for contacting the bicarbonate solution
with the alkaline solution may be equipped with inputs for other reagents
for controlling the pH, stirrers, temperature sensor, and the like.

[0085] The precipitator may be any means suitable to produce the carbonate
or the combination of the carbonate and bicarbonate product from the
bicarbonate solution. Examples of precipitator include, but not limited
to, duct, pipe, tank, or a conduit, or the like that produces the
carbonate product or the combination of the carbonate and the bicarbonate
product from the bicarbonate solution. The precipitator to produce the
carbonate or the combination of the carbonate and bicarbonate product
from the bicarbonate solution may be equipped with inputs for other
reagents for controlling the pH, stirrers, temperature sensor, and the
like.

[0086]FIG. 1B illustrates a flow chart for some embodiments of the
methods and systems related to the production of the bicarbonate
solution. In some embodiments, there is provided a method that includes
producing a bicarbonate solution by contacting carbon dioxide with
carbonate brine and treating the bicarbonate solution with an alkaline
solution to produce a composition comprising carbonate or a combination
of bicarbonate or carbonate. As illustrated in FIG. 1B, in some
embodiments, the bicarbonate brine 103 may be produced from carbonate
brine 102 by dissolving CO2 into the carbonate brine 102. The
reaction may be represented by the following equation:

CO32-+H2O+CO2=2HCO3.sup.

[0087] In some embodiments, there is provided a system configured to
produce the bicarbonate solution and then treat the bicarbonate solution
with the alkaline solution to form carbonate or carbonate and bicarbonate
product. In some embodiments, the systems provided herein include a
reactor system that includes a contactor configured to produce the
bicarbonate solution by contacting the carbon dioxide with the carbonate
brine. The carbon dioxide may be absorbed into the carbonate brine
utilizing a gas mixer/gas absorber described in U.S. Patent Application
Publication No. US 2010-0230293, filed on Jul. 15, 2009, titled,
"CO2 Utilization In Electrochemical Systems," herein incorporated by
reference in its entirety. In some embodiments, the gas mixer/gas
absorber comprises a series of spray nozzles that produces a flat sheet
or curtain of liquid into which the gas is absorbed; in another
embodiment, the gas mixer/gas absorber comprises a spray absorber that
creates a mist and into which the gas is absorbed; in other embodiments,
other commercially available gas/liquid absorber, e.g., an absorber
available from Neumann Systems, Colorado, USA is used. In some
embodiments, the reactor system is operatively connected to a carbon
dioxide gas/liquid contactor configured to dissolve carbon dioxide in the
carbonate brine when the bicarbonate solution is produced which is
further operatively contacted with an alkaline solution, such as
hydroxide generated in the cathode electrolyte of the electrochemical
cell.

[0088] In some embodiments, the alkalinity of the carbonate brine may not
be sufficient to dissolve the CO2 and a base may be added to
increase the alkalinity. In some embodiments, the other base is a natural
base. Such natural bases are well known in the art and include, without
limitation, mineral, microorganism, waste stream, coal ash, and
combination thereof. Examples of the bases that may be used in the
methods and systems of the invention include, but not limited to, organic
bases, such as, formate, acetate, propionate, butyrate, and valerate,
among others; and bacteria, among others. Examples of such microorganisms
are fungi that produce alkaline protease (e.g., the deep-sea fungus
Aspergillus ustus with an optimal pH of 9) and bacteria that create
alkaline molecules (e.g., cyanobacteria such as Lyngbya sp. from the
Atlin wetland in British Columbia, which increases pH from a byproduct of
photosynthesis). In some embodiments, organisms are used to produce
alkalinity, wherein the organisms (e.g., Bacillus pasteurii, which
hydrolyzes urea to ammonia) metabolize a contaminant (e.g. urea) to
produce alkaline solutions (e.g., ammonia, ammonium hydroxide). In
addition, waste streams from various industrial processes may provide
alkalinity. Such waste streams include, but are not limited to, mining
wastes; fossil fuel burning ash (e.g., combustion ash such as fly ash,
bottom ash, boiler slag); slag (e.g. iron slag, phosphorous slag); cement
kiln waste; oil refinery/petrochemical refinery waste (e.g. oil field and
methane seam brines); coal seam wastes (e.g. gas production brines and
coal seam brine); paper processing waste; water softening waste brine
(e.g., ion exchange effluent); silicon processing wastes; agricultural
waste; metal finishing waste; high pH textile waste; and caustic sludge.

[0089] The carbon dioxide used in the system may be obtained from various
industrial sources that release carbon dioxide including carbon dioxide
from combustion gases of fossil fuelled power plants, e.g., conventional
coal, oil and gas power plants, or IGCC (Integrated Gasification Combined
Cycle) power plants that generate power by burning sygas; cement
manufacturing plants that convert limestone to lime; ore processing
plants; fermentation plants; and the like. In some embodiments, the
carbon dioxide is an industrial waste stream including, but not limited
to, flue gas from combustion; a flue gas from a chemical processing
plant; a flue gas from a plant that produces CO2 as a byproduct; or
combination thereof. In some embodiments, the carbon dioxide may comprise
other gases, e.g., nitrogen, oxides of nitrogen (nitrous oxide, nitric
oxide), sulfur and sulfur gases (sulfur dioxide, hydrogen sulfide), and
vaporized materials. In some embodiments, the system includes a gas
treatment system that removes constituents in the carbon dioxide gas
stream before the gas is utilized in the contactor.

[0090] Examples of the carbonate brines have been provided above. The
amount of carbonates present in the brines of the invention may vary. In
some instances, the amount of carbonate present ranges from 50 to 100,000
ppm; or alternatively 100 to 75,000 ppm; or alternatively 500 to 50,000
ppm; or alternatively 1000 to 25,000 ppm.

[0091] As such, in certain embodiments, the carbonate present in the
carbonate brines may comprise 5% by wt or more of carbonates; or 10% by
wt or more of carbonates; or 15% by wt or more of carbonates; or 20% by
wt or more of carbonates; or 30% by wt or more of carbonates; or 40% by
wt or more of carbonates; or 50% by wt or more of carbonates; or 60% by
wt or more of carbonates; or 70% by wt or more of carbonates; or 80% by
wt or more of carbonates; or 90% by wt or more of carbonates; or 99% by
wt or more of carbonates; or 5-99% by wt of carbonates; or 5-95% by wt of
carbonates; or 5-80% by wt of carbonates; or 5-75% by wt of carbonates;
or 5-70% by wt of carbonates; or 5-60% by wt of carbonates; or 5-50% by
wt of carbonates; or 5-40% by wt of carbonates; or 5-30% by wt of
carbonates; or 5-20% by wt of carbonates; or 5-10% by wt of carbonates;
or 10-80% by wt of carbonates; or 10-50% by wt of carbonates; or 10-20%
by wt of carbonates; or 20-80% by wt of carbonates; or 20-50% by wt of
carbonates; or 30-75% by wt of carbonates; or 30-50% by wt of carbonates;
or 40-80% by wt of carbonates; or 50-75% by wt of carbonates; or 50-90%
by wt of carbonates; or 60-80% by wt of carbonates; or 60-95% by wt of
carbonates; or 70-90% by wt of carbonates; or 80-90% by wt of carbonates;
or 5% by wt of carbonates; or 10% by wt of carbonates or 20% by wt of
carbonates; or 25% by wt of carbonates; or 30% by wt of carbonates; or
40% by wt of carbonates; or 50% by wt of carbonates; or 60% by wt of
carbonates; or 70% by wt of carbonates; or 80% by wt of carbonates; or
90% by wt of carbonates.

[0092] It is to be understood that the alkaline solution that is contacted
with the bicarbonate solution is illustrated as the cathode electrolyte
from the electrochemical cell for illustration purposes only (in figures)
and other alkaline solutions as exemplified herein may also be used for
the process and the systems. As illustrated in FIG. 1B, in some
embodiments, the bicarbonate solution 103 is contacted with the cathode
electrolyte outside the cathode chamber (path b) and/or inside the
cathode chamber (path a). For the contact of the bicarbonate solution
inside the cathode chamber, the bicarbonate solution may be added to the
cathode chamber. For the contact of the bicarbonate solution outside the
cathode chamber, the cathode electrolyte may be removed or extracted from
the cathode chamber and is contacted with the bicarbonate solution
outside the cathode chamber. In some embodiments, the bicarbonate
solution 103 is contacted with the cathode electrolyte 101 inside the
cathode chamber (path a) when bicarbonate converts to carbonate and can
be withdrawn from the cathode electrolyte as sodium carbonate (path c).
In some embodiments, the bicarbonate solution 103 is contacted with the
cathode electrolyte outside the cathode chamber where the sodium
hydroxide from the cathode electrolyte is added to the bicarbonate
solution (path b) when bicarbonate converts to carbonate. The carbonate
solution then is treated with divalent cations, such as calcium,
magnesium, or combination thereof, to form carbonate compositions (path
d), such as,
CaCO3/Ca(HCO3)2/MgCO3/Mg(HCO3)2/calcium
magnesium carbonate. In some embodiments, the bicarbonate solution 103 is
added to the cathode electrolyte 101 and the solution is withdrawn from
the cathode electrolyte that includes sodium carbonate, sodium
bicarbonate, and sodium hydroxide. This withdrawn solution may be
circulated back to the cathode electrolyte until the bicarbonate fully
converts to the carbonate. In some embodiments, the solution withdrawn
from the cathode electrolyte (containing sodium carbonate, sodium
bicarbonate, and sodium hydroxide) is circulated back to the bicarbonate
solution before being sent to the cathode electrolyte inside the cathode
chamber (not shown in FIG. 1B).

[0093] In some embodiments, there is provided a method that includes
producing a bicarbonate solution by contacting carbon dioxide with an
alkaline brine and treating the bicarbonate solution with an alkaline
solution to produce a composition comprising carbonate or a combination
of bicarbonate or carbonate. As illustrated in FIG. 1B, in some
embodiments, the bicarbonate solution is produced from an alkaline brine
104 by reacting the alkaline brine with CO2. Such reaction of the
alkaline brine with CO2 can be conducted in the gas/liquid contactor
as described above. As used herein, the "alkaline brine" is any brine
that possesses sufficient alkalinity or basicity to remove one or more
protons from a proton-containing species in solution. The alkalinity of
the alkaline brine may be sufficient to dissolve the CO2 into the
solution and generate bicarbonate solution. Some of the examples of
alkaline brine include, but are not limited to, soda lakes having a pH of
above 10 or 11 found in tropical or subtropical rain-shadow deserts in
North America, interiors of Asia, and techtonic rifting areas in East
African Rift Valley. In some embodiments, the carbonate brines may also
act as alkaline brines. For example, Searles Lake in California includes
carbonates and borates that add alkalinity to the brine. In some
instances, the alkaline brine has a pH that is above neutral pH (i.e.,
pH>7), e.g., the brine has a pH ranging from 7.1 to 12, such as 8 to
12, such as 8 to 11, and including 9 to 11. In some embodiments, while
being basic the pH of the alkaline brine may be insufficient to cause
dissolution of the CO2 into the solution. For example, the pH of the
brine may be 9.5 or lower, such as 9.3 or lower, including 9 or lower. In
such embodiments, a natural base may be added to the alkaline brine. Such
natural bases are well known in the art and are as described above.

[0094] In some embodiments, alkaline brines may also be alkaline hard
brines and include divalent cations, such as calcium and/or magnesium.
Some examples of the soda lakes and soda deserts, typically exhibiting pH
values of >11.5 and may contain divalent cations, are illustrated in
Table II below. One of the largest fossil soda lakes is the Green River
Formation in Wyoming and Utah. The lakes illustrated in Table II below
also have large amounts of carbonate/bicarbonates deposits.

[0095] In some embodiments, the alkaline brine may also contain divalent
cations (alkaline hard brine) and may be treated to remove the divalent
cations before reacting with CO2 (not shown in FIG. 1B). For
example, the alkaline hard brine may be treated with sodium carbonate to
precipitate out the calcium carbonate and/magnesium carbonate and the
alkaline brine after filtration may be treated with CO2 to give
bicarbonate solution.

[0096] As illustrated in FIG. 1B, in some embodiments, the bicarbonate
solution 105 is contacted with the cathode electrolyte outside the
cathode chamber (path e) and/or inside the cathode chamber (path f). In
some embodiments, the bicarbonate solution 105 is contacted with the
cathode electrolyte 101 inside the cathode chamber (path') when
bicarbonate converts to carbonate and can be withdrawn from the cathode
electrolyte as sodium carbonate (path c). In some embodiments, the
bicarbonate solution 105 is contacted with the cathode electrolyte
outside the cathode chamber where the sodium hydroxide from the cathode
electrolyte is added to the bicarbonate solution (path e) when
bicarbonate converts to carbonate. The carbonate solution then is treated
with divalent cations, such as calcium, magnesium, or combination
thereof, to form carbonate compositions (path g), such as,
CaCO3/Ca(HCO3)2/MgCO3/Mg(HCO3)2/calcium
magnesium carbonate. In some embodiments, the bicarbonate solution 105 is
added to the cathode electrolyte 101 and the solution is withdrawn from
the cathode electrolyte that includes sodium carbonate, sodium
bicarbonate, and sodium hydroxide. This withdrawn solution may be
circulated back to the cathode electrolyte until the bicarbonate fully
converts to the carbonate. In some embodiments, the solution withdrawn
from the cathode electrolyte (containing sodium carbonate, sodium
bicarbonate, and sodium hydroxide) is circulated back to the bicarbonate
solution before being sent to the cathode electrolyte inside the cathode
chamber (not shown in FIG. 1B).

[0097] In some embodiments, there is provided a method that includes
reacting bicarbonate hard brine with sodium carbonate to form a carbonate
precipitate; separating the carbonate precipitate from the bicarbonate
hard brine to give a bicarbonate solution; and treating the bicarbonate
solution with an alkaline solution to produce a composition comprising
carbonate or a combination of bicarbonate or carbonate. As illustrated in
FIG. 1B, in some embodiments, the bicarbonate solution may be produced
from bicarbonate brine containing cations or bicarbonate hard brine 106.
Examples of bicarbonate brines have been provided herein. The cations in
the bicarbonate brine may be monovalent cations, such as Na+,
K+, etc. and/or divalent cations, such as Ca2+, Mg2+,
Sr2+, Ba2+, Mn2+, Zn2+, Fe2+, etc. In some
instances, the divalent cations of the brine are alkaline earth metal
cations, e.g., Ca2+, Mg2+. The brine, when serving as a source
of cations, may have Ca2+ present in amounts that vary, ranging from
50 to 100,000 ppm, such as 100 to 75,000 ppm, including 500 to 50,000
ppm, for example 1000 to 25,000 ppm. The brines may have Mg2+
present in amounts that vary, ranging from 50 to 25,000 ppm, such as 100
to 15,000 ppm, including 500 to 10,000 ppm, for example 1000 to 5,000
ppm. In brines where both Ca2+ and Mg2+ are present, the molar
ratio of Ca2+ to Mg2+ (i.e., Ca2+:Mg2+) in the brine
may vary, and in one embodiment may range between 1:1 and 100:1. In some
instance the Ca2+:Mg2+ may be between 1:1 and 1:2.5; 1:2.5 and
1:5; 1:5 and 1:10; 1:10 and 1:25; 1:25 and 1:50; 1:50 and 1:100; 1:100
and 1:150; 1:150 and 1:200; 1:200 and 1:250; 1:250 and 1:500; 1:500 and
1:1000, or a range thereof. For example, the molar ratio of Ca2+ to
Mg2+ in subterranean brines of interest may range between 1:1 and
1:10; 1:5 and 1:25; 1:10 and 1:50; 1:25 and 1:100; 1:50 and 1:500; or
1:100 and 1:1000. In some embodiments, the ratio of Mg2+ to
Ca2+ (i.e., Mg2+:Ca2+) in the brine ranges between 1:1 and
1:2.5; 1:2.5 and 1:5; 1:5 and 1:10; 1:10 and 1:25; 1:25 and 1:50; 1:50
and 1:100; 1:100 and 1:150; 1:150 and 1:200; 1:200 and 1:250; 1:250 and
1:500; 1:500 and 1:1000, or a range thereof. For example, the ratio of
Mg2+ to Ca2+ in the subterranean brines of interest may range
between 1:1 and 1:10; 1:5 and 1:25; 1:10 and 1:50; 1:25 and 1:100; 1:50
and 1:500; or 1:100 and 1:1000. In particular embodiments the
Mg2+:Ca2+ of a brine may be lower than 1:1, such as 1:2, 1:3,
1:4, 1:10, 1:100 or lower.

[0098] As illustrated in FIG. 1B, in some embodiments, the bicarbonate
hard brines 106 are treated with sodium carbonate to precipitate out the
carbonate precipitate, such as, but not limited to, calcium carbonate,
magnesium carbonate, or combination thereof. After removing the divalent
cations from the bicarbonate hard brine 106, the remaining bicarbonate
solution 107 is contacted with the cathode electrolyte 101 inside the
cathode chamber (path h) when bicarbonate converts to carbonate and can
be withdrawn from the cathode electrolyte as sodium carbonate (path c).
In some embodiments, the bicarbonate solution 107 is contacted with the
cathode electrolyte outside the cathode chamber where the sodium
hydroxide from the cathode electrolyte is added to the bicarbonate
solution (path i) when bicarbonate converts to carbonate. The carbonate
solution then is treated with divalent cations, such as calcium,
magnesium, or combination thereof, to form carbonate compositions (path
j), such as,
CaCO3/Ca(HCO3)2/MgCO3/Mg(HCO3)2/calcium
magnesium carbonate. In some embodiments, the bicarbonate solution 107 is
added to the cathode electrolyte 101 and the solution is withdrawn from
the cathode electrolyte that includes sodium carbonate, sodium
bicarbonate, and sodium hydroxide. This withdrawn solution may be
circulated back to the cathode electrolyte until the bicarbonate fully
converts to the carbonate. In some embodiments, the solution withdrawn
from the cathode electrolyte (containing sodium carbonate, sodium
bicarbonate, and sodium hydroxide) is circulated back to the bicarbonate
solution before being sent to the cathode electrolyte inside the cathode
chamber (not shown in FIG. 1B).

[0099] In some embodiments, there is provided a method that includes
producing a bicarbonate solution from a subterranean brine, subsurface
brine, or surface brine and treating the bicarbonate solution with an
alkaline solution to produce a composition comprising carbonate or a
combination of bicarbonate or carbonate. In some embodiments, there is
provided a method that includes producing a bicarbonate solution from an
evaporite and treating the bicarbonate solution with an alkaline solution
to produce a composition comprising carbonate or a combination of
bicarbonate or carbonate. As illustrated in FIG. 1B, in some embodiments,
the bicarbonate solution may be derived from or is a naturally occurring
bicarbonate brine 108. The naturally occurring bicarbonate brine may be
obtained from a subterranean, subsurface, or surface location or is
obtained from an evaporite or an ophiolite. Examples of some of the
naturally occurring subterranean brines, subsurface brines, or surface
brines are described above. The evaporite can be used in its conventional
sense and includes a mineral deposit which forms when a restricted
alkaline body of water (e.g., lake, pond, lagoon, etc.) is dehydrated by
evaporation which results in concentration of ions from the alkaline body
of water to precipitate out and form a mineral deposit, e.g., the crust
along Lake Natron in Africa's Great Rift Valley. Naturally occurring
evaporites may be found in evaporite basins, which can be classified into
six different depositional settings: continental grabens, geosynclinals
basins, artesian basins, stranded marine waters, and arid drainage
basins. Ions found within evaporites may be derived from the weathering
of the rocks and sediments with the watershed and from various types of
source water (meteoric, phreatic, marine, etc.). As such, the composition
of evaporites may vary. For example, evaporites may contain halides
(e.g., halite, sylvite, fluorite, etc.), sulfates (e.g., gypsum,
anhydrite, barite, etc.), nitrates (nitratine, niter, etc.), borates
(e.g., borax), carbonates and bicarbonates (e.g., calcite, aragonite,
dolomite, trona, etc.), or combination thereof, among others. Therefore,
the brines obtained from evaporites may provide a source of carbonate,
bicarbonate, as well as alkalinity.

[0100] In some embodiments, the evaporite or ophiolites may also be a
source of one or more cations. In some embodiments, the cations may be
monovalent cations, such as Na+, K+. In some embodiments, the
cations are divalent cations, such as Ca2+, Mg2+, Sr2+,
Ba2+Mn2+, Zn2+, or Fe2+. The source of divalent
cations from evaporites may be in the form of mineral salts, such as
sulfate salts (e.g., calcium sulfate), or borate salts (e.g., borax). In
some instances, divalent cations of the evaporite are alkaline earth
metal cations, e.g., Ca2+, Mg2+.

[0101] In certain embodiments, the evaporites contain borate. Borates
present in evaporites of the invention may be any borate salt, e.g.,
Na3BO3. The amount of borate present in evaporites of the
invention may vary. In some instances, the amount of borate that is
present in the evaporite ranges from 1% to 95% (w/w), such as 5% to 90%
(w/w), such as 10% to 90% (w/w), including about 15% to 85% (w/w), for
instance about 20% to 75% (w/w), such as 25% to 75% (w/w), such as 25% to
60% (w/w), including about 25% to 50% (w/w).

[0102] Evaporites or ophiolites may be obtained using any convenient
protocol. For instance, naturally forming surface or subsurface
evaporites may be obtained by quarry excavation using conventional
earth-moving equipment, e.g., bulldozers, front-end loaders, back hoes,
etc. In these embodiments, evaporites or ophiolites may also be further
processed after excavation to separate each mineral as desired, such as
by rehydration followed by sequential precipitation or by density-based
separation methods. In other embodiments, evaporites may be obtained by
pond precipitation. In these embodiments, a source evaporite aqueous
composition (e.g., surface or subsurface brine) may first be obtained,
such as by a surface turbine motor pump or subsurface brine pump, and
subsequently dehydrated to produce the evaporite. In some embodiments,
the composition of the source evaporite aqueous composition may be
adjusted (i.e., adding or removing components, as desired) prior to
dehydrating the source water to produce an evaporite of a desired
composition. The evaporite may be used as is or are subjecting to
processes such as, but not limited to, crushing, milling, grinding, etc.
to reduce the size of the rocks or to make a fine powder. The crushed or
milled bicarbonate evaporite may be dissolved in water to make the
bicarbonate solution. In embodiments, where the evaporite is a carbonate
mineral, the carbonate may be converted to bicarbonate by treating with
CO2 before being used as the bicarbonate solution in the systems and
methods of the invention.

[0103] In some embodiments, the evaporites are crushed, milled, grounded,
or combination thereof, are dissolved in water and the solution is used
as is for contacting with the cathode electrolyte in accordance with the
methods and systems of the invention. In some embodiments, evaporites may
be processed to remove other elements, such as divalent cations, borates,
etc., from the bicarbonate before contacting with the cathode
electrolyte.

[0104] In some embodiments, the pH of the bicarbonate solution is greater
than 7; or 7-12; or 7-10; or 7-8; or greater than 10; or 8-12; or 8-10;
or 9-14; or 9-12; or 9-10; or 10-14; or 10-12; or 11-14. In addition to
carbonates, the bicarbonate solution may also contain other anions, such
as, but are not limited to, sulfate, phosphate, chloride etc. In some
embodiments, the bicarbonate solution may include large amounts of sulfur
which may be present in various forms, such as, but are not limited to,
hydrogen sulfide (H2S), sulfite (SO32-), and thionates
(S4O62-). These sulfate forms may be removed before using
the bicarbonate solution in the methods and systems provided herein.

[0105] In some embodiments, the bicarbonate solution includes one or more
of elements including, but not limited to, aluminum, barium, cobalt,
copper, iron, lanthanum, lithium, mercury, arsenic, cadmium, lead,
nickel, phosphorus, scandium, titanium, zinc, zirconium, molybdenum,
and/or selenium. In some embodiments, the bicarbonate solution includes
one or more of elements including, but not limited to, lanthanum,
mercury, arsenic, lead, and selenium. In some embodiments, the
bicarbonate solution are processed to remove one or more of the elements,
such as, lithium, iron, etc. and the remaining solution is used in the
systems and methods provided herein, and/or the solution may be used in
the systems and methods provided herein and then processed to remove one
or more of these elements. The foregoing elements may be considered as
markers for identifying reaction products, i.e., carbonate compositions
of the invention derived from bicarbonate brines or bicarbonate solution.

[0106] As illustrated in FIG. 1B, in some embodiments, the bicarbonate
solution 108 is contacted with the cathode electrolyte outside the
cathode chamber (path m) and/or inside the cathode chamber (path k). In
some embodiments, the bicarbonate solution 108 is contacted with the
cathode electrolyte 101 inside the cathode chamber (path k) when
bicarbonate converts to carbonate and can be withdrawn from the cathode
electrolyte as sodium carbonate (path c). In some embodiments, the
bicarbonate solution 108 is contacted with the cathode electrolyte
outside the cathode chamber where the sodium hydroxide from the cathode
electrolyte is added to the bicarbonate solution (path m) when
bicarbonate converts to carbonate. The carbonate solution then is treated
with divalent cations, such as calcium, magnesium, or combination
thereof, to form carbonate compositions (path n), such as,
CaCO3/Ca(HCO3)2/MgCO3/Mg(HCO3)2/calcium
magnesium carbonate. In some embodiments, the bicarbonate solution 108 is
added to the cathode electrolyte 101 and the solution is withdrawn from
the cathode electrolyte that includes sodium carbonate, sodium
bicarbonate, and sodium hydroxide. This withdrawn solution may be
circulated back to the cathode electrolyte until the bicarbonate fully
converts to the carbonate. In some embodiments, the solution withdrawn
from the cathode electrolyte (containing sodium carbonate, sodium
bicarbonate, and sodium hydroxide) is circulated back to the bicarbonate
solution before being sent to the cathode electrolyte inside the cathode
chamber (not shown in FIG. 1B).

[0107] It is to be understood that any number of variations of the
addition of the bicarbonate solution to the cathode electrolyte
including, but not limited to, inside the cathode chamber, and/or outside
the cathode chamber, and/or recirculation of the bicarbonate solution
inside the cathode chamber and back to the bicarbonate solution, etc. are
well within the scope of this invention.

[0108] In some embodiments, the sodium carbonate obtained from the cathode
electrolyte (path c) is treated with divalent cations, or a brine
containing divalent cations (hard brine), such as calcium chloride
containing brine, to precipitate out calcium carbonate, magnesium
carbonate, or combination thereof. The remaining raw brine may be
circulated back to the electrochemical cell (not shown in FIG. 1B). The
raw brine may be circulated to any of the cathode electrolyte, anode
electrolyte, or the brine compartment of the electrochemical cell
depending on the design of the electrochemical cell.

[0109] The methods and systems provided herein may produce bicarbonate
solution from either of the methods and systems described in FIG. 1B or a
combination thereof. For example, the source of the bicarbonate solution
that is contacted with the cathode electrolyte inside the cathode chamber
and/or outside the cathode chamber may be the bicarbonate solution 103,
105, 107, and/or 108.

[0110] The bicarbonate solution produced by the methods and systems as
described above or other brines used in the processes to produce the
bicarbonate solution, may be treated, altered, or modified before the
bicarbonate solution is contacted with the cathode electrolyte. The
alteration or the modification of the bicarbonate solution and/or the
brine may include processes, such as, but not limited to, sedimentation,
centrifugation, filtration, etc. The alteration or the modification of
the bicarbonate solution and/or the brine may also include treating the
solution and/or the brine to remove or add components. In some
embodiments, modifying the bicarbonate solution and/or the brine includes
concentrating or diluting a solution and/or brine to achieve a desired
ionic strength or component concentration. In some embodiments, modifying
the solution and/or the brine may include heating or cooling prior to or
during the reaction. The solution and/or the brine may be treated in
situ. In some embodiments, modifying the solution and/or the brine
includes mixing two or more different solutions and/or the brines to
produce a brine mixture, where each of the two or more solutions and/or
the brines is obtained from distinct sources (e.g., man-made or synthetic
brine and subterranean brine or brines from separate subterranean
locations). The amount of each of the solution and/or the brine in the
mixture may vary as desired, ranging in some instances from 0.1% to 99.9%
by volume, or 0.1-75%; or 0.1-50%; or 0.1-30%; or 5-95%; or 5-75%; or
5-50%; or 10-99%; or 10-75%; or 10-50%; 10-25%; or 25-90%; or 25-75%; or
25-50%; or 50-90%; or 50-75%; or 75-90%; or 75-80% by volume. Two or more
solutions and/or the brines may be mixed by any convenient mixing
protocol, such as using agitator drives, counterflow impellers, turbine
impellers, anchor impellers, ribbon impellers, axial flow impellers,
radial flow impellers, hydrofoil mixers, aerators, among others. The
modification of the bicarbonate solution may be carried out in the
reactor system.

[0111] In some embodiments, the methods of the invention further include
obtaining brine from a subterranean location before processing or before
using in the methods and the systems. In some embodiments, there is
provided a method including obtaining a subterranean brine; producing a
bicarbonate solution from the subterranean brine; and treating the
bicarbonate solution to produce a product including carbonate or
combination of carbonate and bicarbonate. A subterranean brine can be
obtained by any convenient protocol, such as for example by pumping the
subterranean brine from the subterranean location using, for example a
down-well turbine motor pump, a geothermal well pump or a surface-located
brine pump. In some embodiments, obtaining the subterranean brine may
include pumping the subterranean brine from the underground location and
storing it in an above-ground storage basin. The above-ground storage
basin may be any convenient storage basin. In some embodiments, the
above-ground storage basin may be a naturally-occurring geological
structure, such as, a tailings pond or dried riverbed or may be a manmade
structure, such as a storage tank. Where desired, the subterranean brine
may be stored in the above-ground storage basin for a period of time
following pumping from the subterranean location. For example, the
subterranean brine may be stored for a period of time ranging from 1 to
1000 days or longer, such as 1 to 500 days or longer, and including 1 to
100 days or longer. In these embodiments, the subterranean brine may be
stored at a temperature ranging from 1 to 75° C., such as 10 to
50° C. and including 10 to 25° C. In some embodiments, the
subterranean brine may be left in the subterranean location (e.g., in an
underground well) until needed and pumped from the underground location
directly into the cathode electrolyte inside and/or outside the cathode
chamber or pumped from the underground location for further processing
and/or modification to form bicarbonate brine. In some embodiments, the
subterranean brine may be left in the subterranean location (e.g., in an
underground well) and contacting and/or other operations may be performed
underground. Brines may be treated prior to, during or after storage for
any length of time.

[0112] In some embodiments, the composition of the brine mixture may be
determined, monitored or assessed after preparing the brine or after
obtaining brine from the subterranean location or after mixing the two or
more subterranean brines together. Based on the determined composition of
the brine or the brine mixture, the brine may be further treated. Where
desired, monitoring and modification may be performed using real-time
protocols, such that these two processes are occurring continuously to
provide the desired brine.

[0113] Changes in the brine that may be achieved upon treatment may vary
greatly. For example, the chemical makeup of the brine may be modified,
e.g., via production of new chemical species in the brine or augmentation
or other modification of the concentration of a chemical species already
present in the brine. In some embodiments, one or more components of the
brine may be removed from the brine. The brine may also be modified to
remove one or more elements, such as, lithium, iron, aluminum, etc. which
find use in other applications.

[0114] In some embodiments, the elements may be added to the bicarbonate
solution prior to contacting the bicarbonate solution with the cathode
electrolyte. Where desired, the elements may be added to the bicarbonate
solution at more than one time during methods of the invention (e.g.,
before, during or after contacting the bicarbonate solution with the
cathode electrolyte). In some embodiments, the elements added to the
bicarbonate solution range from 0.01 to 100.0 grams/liter of solution,
such as from 1 to 100 grams/liter of solution, for example 5 to 80
grams/liter of solution, including 5 to 50 grams/liter of solution.

[0115] In some embodiments, if the concentration of bicarbonate in the
solution is less than optimal for the formation of the sodium carbonate
after contacting with the cathode electrolyte, then bicarbonate may be
added to the solution to increase the concentration of the bicarbonate in
the solution. In some embodiments, if the bicarbonate in the solution is
an excess of bicarbonate then the solution may be diluted to reduce the
concentration of the bicarbonate in the bicarbonate solution. In some
embodiments, the temperature, pressure, and/or pH of the bicarbonate
solution may be optimized.

[0116] In some embodiments, the composition of the brine, such as, the
subterranean, subsurface or surface brine, may be considered to be less
than optimal when the brine contains bacterial content, such as where the
concentration of bacteria is 1×105 cfu/ml or greater, such as
5×105 cfu/ml or greater, such as 1×106 cfu/ml or
greater, such as 5×106 cfu/ml or greater, including
1×107 cfu/ml or greater. As such, in some embodiments, the
composition of the brine may be modified to reduce or eliminate the
amount of bacterial content in the brine. The bacterial concentration of
the brine may be decreased by 5-fold or more, such as 10-fold or more,
such as 100-fold or more, such as 1000-fold or more, such as 10.000-fold
or more, such as 100.000-fold or more, including 1,000,000-fold or more.
The bacterial content may be reduced or eliminated by treating the brine
with any convenient protocol, such as increasing the temperature of the
brine. In some embodiments, methods of the invention also include
determining and assessing the composition of the brine after treating the
brine with a protocol for reducing or eliminating bacterial content. In
some embodiments, the bacterial concentration of the brine is reduced or
eliminated by adding an amount of a bactericidal composition.
Bactericidal compositions may be any convenient composition which
inactivates or kills bacteria and may include, but are not limited to,
bacterial disinfectants (e.g., dichloroisocyanurate, iodopovidone,
isopropanol, triclosan, tricholorophenol, cetyl trimethyammonium bromide,
peroxides, etc.), antibiotics (e.g., penicillin, cephalosporins,
monobactams, daptomycin, fluoroquinolones, metronidazole, nitrofurantoin,
etc.), antiseptics (e.g., potassium hypochlorite, sodium
benzenesulfochlroamide, Lugol's solution, urea perhydrate, sorbic acid,
hexachlorophene, Dibromol, etc.). The bactericidal composition may be
added to the brine by any convenient protocol, such as a solid, an
aqueous composition, a liquid, etc.

[0117] In some embodiments, the bacterial concentration of the brine or
the bicarbonate solution is reduced or eliminated by adjusting the
temperature of the brine. The temperature of the brine or the solution
may be adjusted by any convenient protocol, such as by heat coils,
Peltier thermoelectric devices, solar heating devices, water baths, oil
baths, gas-power water boilers, etc. Adjusting the temperature of the
brine to reduce or eliminate bacterial content may vary, such as
increasing the temperature of the brine by 5° C. or more, such as
10° C. or more, such as 15° C. or more, such as 25°
C. or more, such as 50° C. or more, such as 75° C. or more,
including 100° C. or more. In other embodiments, the bacterial
concentration of the brine or the bicarbonate solution is reduced or
eliminated by irradiating the brine with electromagnetic radiation, e.g.,
UV light. The brine or the bicarbonate solution may be irradiated with
electromagnetic radiation by any convenient protocol, such as by using
one or more lamps or lasers. In some instances, the brine or the
bicarbonate solution may be irradiated in the storage basin, with or
without stirring. In other instances, the subterranean brine may be
pumped through UV-transparent (e.g., quartz) pipes and irradiated by one
or more lamps or laser while the subterranean brine is pumped. The
duration of irradiation may vary depending on the volume of the brine or
the bicarbonate solution and the desired extent of treatment. In some
embodiments, the brine or the bicarbonate solution may be irradiated for
0.5 hours or more, such as 1 hour or more, such as 2 hours or more, such
as 5 hours or more, such as 10 hours or more, including 24 hours or more.

[0118] In some embodiments, modifying the bicarbonate brine or the
bicarbonate solution includes concentrating bicarbonate. The
concentration of the bicarbonate in the brine or the solution may be
accomplished using any convenient protocol, e.g., distillation,
evaporation, among other protocols (e.g., so as to decrease the total
volume of the brine while keeping the mass of carbonate constant). In
some embodiments, the brine or the solution may be concentrated by the
use of evaporation ponds to reduce the total volume of water and volatile
organic substances in the brine. In some embodiments, the brine or the
solution may be concentrated by using heat from a power plant in order to
evaporate water and volatile organic substances. In some embodiments,
bicarbonate in the brine or the solution may be concentrated by adding
bicarbonate to the brine (i.e., so as to increase the mass of bicarbonate
while keeping the total volume of the bicarbonate brine constant).
Bicarbonate may be added to the brine or the solution by any suitable
protocol. For example, sodium bicarbonate may be added to the brine or
the solution as a solid or a slurry. In some instances, sodium
bicarbonate may be dissolved in an aqueous solution and the aqueous
solution added to the brine. In other embodiments, methods of the
invention may include decreasing the bicarbonate concentration in the
bicarbonate brine or the bicarbonate solution. As such, the concentration
of bicarbonate in the brine may be decreased, e.g., by 0.1M or more, such
as by 0.5 M or more, such as by 1 M or more, such as by 2 M or more, such
as by 5 M or more, including by 10 M or more. Decreasing the
concentration of bicarbonate in the brine or the solution may be
accomplished using any convenient protocol for example, diluting the
brine with diluent (e.g., water).

[0119] The initial temperature of the brine or the solution may vary
depending on the source of the brine (e.g., subterranean brine), ranging
from -5 to 110° C., such as from 0 to 100° C., such as from
10 to 80° C., and including from 20 to 60° C. In certain
embodiments, the temperature of the brine or the solution may be adjusted
(i.e., increased or decreased) as desired, e.g., by 5° C. or more,
such as 10° C. or more, such as 15° C. or more, such as
25° C. or more, such as 50° C. or more, such as 75°
C. or more, including 100° C. or more. Where desired, the
temperature of the bicarbonate brine or the bicarbonate solution may be
adjusted to a temperature which is equivalent to the temperature of the
cathode electrolyte. The temperature of the brine or the solution may be
adjusted using any convenient protocol, such as, for example, a thermal
heat exchanger, electric heating coils, Peltier thermoelectric devices,
gas-powered boilers, among other protocols.

[0120] In certain embodiments, the temperature of the brine or the
bicarbonate solution may be raised using energy generated from low or
zero carbon dioxide emission sources, e.g., solar energy source, wind
energy source, hydroelectric energy source, etc. In certain embodiments,
the temperature of a brine or the bicarbonate solution may be lowered and
the excess heat energy used for a beneficial purpose. In some
embodiments, excess thermal energy of the brine or the bicarbonate
solution may be used to drive one or more processes of this invention.
Heat energy may be converted to electrical energy or used as thermal
energy. The thermal energy of the brine or the bicarbonate solution may
be collected via a heat exchanger (e.g., a vertical or horizontal closed
loop) and transferred to a process of this invention, for example
dewatering the precipitate of this invention. Thermal energy of the brine
or the bicarbonate solution may be used to generate electrical power
(e.g., steam generator). In some embodiments, thermal energy from the
brine or the bicarbonate solution may be used to heat the precipitate or
the product of this invention in order to dry that precipitate or the
product (e.g., dry an aggregate or the formed building material). In some
embodiments, thermal energy from a geothermal source may be converted to
electrical energy and is used to drive the electrochemical process.

B. Methods and Systems Including an Electrochemical Cell

[0121] In one aspect, there is provided a system including an anode
electrolyte in contact with an anode; a cathode electrolyte in contact
with a cathode; and a contact system operably connected to the cathode
electrolyte configured to contact a bicarbonate solution to the cathode
electrolyte. In some embodiments, the bicarbonate solution may be
contacted with the cathode electrolyte of any electrochemical cell that
produces an alkaline solution in the cathode electrolyte. In some
embodiments, the electrochemical process is a chloralkali process where
chlorine is produced at the anode. The chloralkali process is well known
in the art. In some embodiments, the electrochemical cell is a hydrolysis
process where oxygen is produced at the anode. Some embodiments of the
methods and systems using the electrochemical cell are described herein.
Such electrochemical cells are in no way limiting to the scope of the
invention. It is to be understood that any electrochemical cell that
produces an alkali in the cathode electrolyte is well within the scope of
the invention. The bicarbonate solution and the methods of producing the
bicarbonate solution have been described herein.

[0122] FIGS. 2A, 2B, 3A, and 3B illustrate some embodiments of the systems
and methods provided herein, where the systems 200 and 300 include a
cathode chamber including a cathode 201 in contact with a cathode
electrolyte 202 and an anode chamber including an anode 204 and an anode
electrolyte 203. In FIGS. 2A, 2B, 3A, and 3B, the cathode chamber is
separated from the anode chamber by a first cation exchange membrane
(CEM) 206. FIGS. 3A and 3B illustrate the system 300 including an anode
204 that is separated from the anode electrolyte 203 by a second cation
exchange membrane 212 that is in contact with the anode 204. FIGS. 2A and
3A illustrate some embodiments where the bicarbonate solution 205 is
added to the cathode electrolyte 202 inside the cathode chamber. FIGS. 2B
and 3B illustrate some embodiments where the bicarbonate solution 205 is
contacted with the hydroxide from the cathode electrolyte 202 outside the
cathode chamber.

[0123] In systems 200 and 300 as illustrated in FIGS. 2A, 2B, 3A, and 3B,
the first cation exchange membrane 206 is located between the cathode 201
and anode 204 such that it separates the cathode electrolyte 202 from the
anode electrolyte 203. In some embodiments, the hydrogen gas produced at
the cathode is directed to the anode through a hydrogen gas delivery
system 207, and is oxidized to hydrogen ions at the anode. Thus, as is
illustrated in FIGS. 2A, 2B, 3A, and 3B, on applying a relatively low
voltage, e.g., less than 2V or less than 1V, across the anode 204 and
cathode 201, hydroxide ions (OH-) and hydrogen gas (H2) are
produced at the cathode 201; the hydrogen gas is directed from the
cathode 201 to the anode 204; and hydrogen gas is oxidized at the anode
204 to produce hydrogen ions at the anode 204, without producing a gas at
the anode. In some embodiments, utilizing hydrogen gas at the anode from
hydrogen generated at the cathode eliminates the need for an external
supply of hydrogen. In some embodiments, utilizing hydrogen gas at the
anode from hydrogen generated at the cathode reduces the utilization of
energy by the system to produce the alkaline solution.

[0124] In some embodiments, as illustrated in FIGS. 2A, 2B, 3A, and 3B,
under the applied voltage 209 across the anode 204 and the cathode 201,
hydroxide ions are produced at the cathode 201 and migrate into the
cathode electrolyte 202, and hydrogen gas is produced at the cathode. In
certain embodiments, the hydrogen gas produced at the cathode 201 is
collected and directed to the anode, e.g., by a hydrogen gas delivery
system 207, where it is oxidized to produce hydrogen ions at the anode.
Under the applied voltage 209 across the anode 204 and cathode 201,
hydrogen ions produced at the anode 204 migrate from the anode 204 into
the anode electrolyte 203 to produce an acid, e.g., hydrochloric acid. In
some embodiments, the first cation exchange membrane 206 may be selected
to allow passage of cations therethrough while restricting passage of
anions therethrough. Thus, as is illustrated in FIGS. 2A, 2B, 3A, and 3B,
on applying the low voltage across the anode 204 and cathode 201, cations
in the anode electrolyte 203, e.g., sodium ions in the anode electrolyte
migrate into the cathode electrolyte through the first cation exchange
membrane 206, while anions in the cathode electrolyte 202, e.g.,
hydroxide ions, and/or carbonate ions, and/or bicarbonate ions, are
prevented from migrating from the cathode electrolyte through the first
cation exchange membrane 206 and into the anode electrolyte 203.

[0125] Thus, as is illustrated in FIGS. 2A, 2B, 3A, and 3B, where the
anode electrolyte 203 includes an aqueous salt solution such as sodium
chloride in water, a solution, e.g., an alkaline solution, is produced in
the cathode electrolyte 202 including cations, e.g., sodium ions, that
migrate from the anode electrolyte 203, and anions, e.g., hydroxide ions
produced at the cathode 201. As illustrated in FIGS. 2A and 3A, in some
embodiments, the bicarbonate solution 205 may be contacted with the
cathode electrolyte 202 inside the cathode chamber. The bicarbonate ions
upon reaction with the sodium hydroxide in the cathode electrolyte
produce carbonate ions. Concurrently, in the anode electrolyte 203, an
acid, e.g., hydrochloric acid is produced from hydrogen ions migrating
from the anode 204 and anions, e.g., chloride ions, present from the
anode electrolyte. As illustrated in FIGS. 2B and 3B, in some
embodiments, the bicarbonate solution 205 may be contacted with the
cathode electrolyte 202 containing sodium hydroxide outside the cathode
chamber. The bicarbonate ions upon reaction with the sodium hydroxide in
the cathode electrolyte produce carbonate ions. Such
carbonate/bicarbonate containing solution is further processed as
described herein to make carbonate compositions.

[0126] With reference to FIGS. 3A and 3B, an anode comprising a second
cation exchange membrane 212 is utilized to separate the anode 204 from
the anode electrolyte 203 such that on a first surface, the cation
exchange membrane 212 is in contact with the anode 204, and an opposed
second surface it is in contact with the anode electrolyte 203. In some
embodiments, since the second cation exchange membrane 212 is permeable
to cations, e.g., hydrogen ions, the anode 204 is in electrical contact
with the anode electrolyte 203 through the second cation exchange
membrane 212.

[0127] Thus, in some embodiments of FIGS. 3A and 3B, as with the
embodiments illustrated for FIGS. 2A and 2B, on applying the low voltage
across the anode 204 and cathode 201, hydrogen ions, produced at the
anode 204 from oxidation of hydrogen gas at the anode, migrate through
the second cation exchange membrane 212 into the anode electrolyte 203.
At the same time, cations in the anode electrolyte 203, e.g., sodium ions
in the anode electrolyte comprising sodium chloride, migrate from the
anode electrolyte 203 into the cathode electrolyte 202 through the first
cation exchange membrane 206, while anions in the cathode electrolyte
202, e.g., hydroxide ions, and/or carbonate ions, and/or bicarbonate
ions, are prevented from migrating from the cathode electrolyte 202 to
the anode electrolyte 203 through the first cation exchange membrane 206.
Also, in some embodiments of FIGS. 3A and 3B, hydrogen ions migrating
from the anode 204 through the second cation exchange membrane 212 into
the anode electrolyte 203 may produce an acid, e.g., hydrochloric acid
with the anions, e.g., chloride ions, present in the anode electrolyte;
wherein the cathode electrolyte 202, an alkaline solution is produce from
anions present in the cathode electrolyte 202 and cations, e.g., sodium
ions, that migrate from the anode electrolyte 203 to the cathode
electrolyte 202 through the first cation exchange membrane 206. In some
embodiments, the voltage across the anode 204 and cathode 201 is adjusted
to a level such that hydroxide ions and hydrogen gas are produced at the
cathode 201 without producing a gas, e.g., chlorine or oxygen, at the
anode 204.

[0128] As illustrated in FIGS. 2A and 3A, in some embodiments, the cathode
electrolyte 202 is operatively contacted with a supply of bicarbonate
solution 205. In some embodiments, the bicarbonate solution may be
naturally occurring bicarbonate brine. In some embodiments, the
bicarbonate solution may be processed from other natural substances to
produce the bicarbonate solution. Such bicarbonate solutions have been
described in detail herein.

[0129] As illustrated in FIGS. 2A, 2B, 3A, and 3B, in some embodiments,
the anode electrolyte 203 comprises a salt solution that includes sodium
ions and chloride ions; the system 200, 300 is configured to produce the
alkaline solution in the cathode electrolyte 202 while also producing
hydrogen ions at the anode 204, with less than 2V, or less than 1V, or
between 0.1V-1V, or between 0.1-2V, across the anode 204 and cathode 201,
without producing a gas at the anode 204; the system 200, 300 is
configured to migrate hydrogen ions from the anode 204 into the anode
electrolyte 203; the anode electrolyte 203 comprises an acid; the system
200, 300 is configured to produce hydroxide, and/or bicarbonate ions,
and/or carbonate ions in the cathode electrolyte 202; migrate hydroxide
ions from the cathode 201 into the cathode electrolyte 202; migrate
cations, e.g., sodium ions, from the anode electrolyte 203 into the
cathode electrolyte 202 through the first cation exchange membrane 206;
hydrogen gas is provided to the anode; a hydrogen gas delivery system 207
is configured to direct hydrogen gas from the cathode to the anode; the
cathode electrolyte 202 in the system 200, 300 is configured to be
contacted with a bicarbonate solution 205 inside the cathode chamber to
produce bicarbonate, carbonate, or mixture thereof depending on the pH of
the cathode electrolyte; in some embodiments, the sodium hydroxide
produced by the cathode electrolyte 202 is contacted with the bicarbonate
solution 205 outside the cathode chamber to produce bicarbonate,
carbonate, or mixture thereof.

[0130] In some embodiments, as illustrated in FIGS. 4A and 4B, the system
400 comprises a cathode chamber including a cathode 201 in contact with a
cathode electrolyte 202 and an anode chamber including an anode 204 in
contact with an anode electrolyte 203. In this system, the cathode
electrolyte 202 comprises a salt solution that functions as the cathode
electrolyte as well as a source of chloride and sodium ions for the
alkaline and acid solution produced in the system. In this system, the
cathode electrolyte 202 is separated from the anode electrolyte 203 by an
anion exchange membrane (AEM) 213 that allows migration of anions, e.g.,
chloride ions, from the salt solution to the anode electrolyte 203. As is
illustrated in FIGS. 4A and 4B, the system includes a hydrogen gas
delivery system 207 configured to provide hydrogen gas to the anode 204.

[0131] Referring to FIGS. 4A and 4B, on applying a voltage across the
anode and the cathode, protons produced at the anode 204 from oxidation
of hydrogen enter into the anode electrolyte 203 from where they may
attempt to migrate to the cathode electrolyte 202 across the anion
exchange membrane 213. However, as the anion exchange membrane 213 may
block the passage of cations, the protons may accumulate in the anode
electrolyte 203. At the same time, however, the anion exchange membrane
213 being pervious to anions may allow the migration of anions, e.g.,
chloride ions from the cathode electrolyte 202 to the anode electrolyte
203. Thus, in some embodiments, chloride ions may migrate to the anode
electrolyte 203 to produce hydrochloric acid in the anode electrolyte
203. In this system, the voltage across the anode 204 and cathode 201 is
adjusted to a level such that hydroxide ions and hydrogen gas are
produced at the cathode 201 without producing a gas, e.g., chlorine or
oxygen, at the anode 204. In some embodiments, since cations may not
migrate from the cathode electrolyte across the anion exchange membrane
213, sodium ions may accumulate in the cathode electrolyte 202 to produce
an alkaline solution with hydroxide ions produced at the cathode. In some
embodiments where bicarbonate solution is contacted with the cathode
electrolyte, sodium ions may also produce sodium bicarbonate and or
sodium carbonate in the cathode electrolyte.

[0132] As illustrated in FIGS. 4A and 4B, in some embodiments, the anode
electrolyte 203 comprises a salt solution that includes sodium ions and
chloride ions; the system 400 is configured to produce the alkaline
solution in the cathode electrolyte 202 while also producing hydrogen
ions at the anode 204, with less than 1V across the anode 204 and cathode
201, without producing a gas at the anode 204; the system 400 is
configured to migrate chloride ions from the cathode electrolyte 202 to
the anode electrolyte 203 through the anion exchange membrane 213;
hydrogen gas is provided to the anode; and a hydrogen gas delivery system
207 is configured to direct hydrogen gas from the cathode to the anode;
the anode electrolyte 203 comprises an acid; migrate hydroxide ions from
the cathode 201 into the cathode electrolyte 202; the system 400 is
configured to produce hydroxide, and/or bicarbonate ions, and/or
carbonate ions in the cathode electrolyte 202.

[0133] Referring to FIGS. 5A and 5B herein, the system 500 in some
embodiments includes an anode chamber including an anode 204 in contact
with an anode electrolyte 203 and a cathode chamber including a cathode
201 in contact with a cathode electrolyte 202. The system 500 includes a
third electrolyte disposed between the anion exchange membrane 213 and
the first cation exchange membrane 206. The third electrolyte is a salt
solution 211. In some embodiments, the system includes a gas delivery
system 207 configured to deliver hydrogen gas to the anode 204. In some
embodiments, the hydrogen gas is obtained from the cathode 201. In the
system, the anode 204 is configured to produce protons, and the cathode
201 is configured to produce hydroxide ions and hydrogen gas when a low
voltage 209, e.g., less than 2V, is applied across the anode and the
cathode. In the system, a gas is not produced at the anode 204.

[0134] In some embodiments, the system is as illustrated in FIGS. 5A and
5B, the first cation exchange membrane 206 is positioned between the
cathode electrolyte 202 and the third electrolyte, the salt solution 211;
and an anion exchange membrane 213 is positioned between the salt
solution 211 and the anode electrolyte 203 in a configuration where the
anode electrolyte 203 is separated from the anode 204 by second cation
exchange membrane 212. In some embodiments, the second cation exchange
membrane is optional. The second cation exchange membrane may prevent the
anode from corrosion by the acid generated in the anode electrolyte.
Therefore, systems where the anode does not have a second cation exchange
membrane, are well within the scope of the invention. In the system, the
second cation exchange membrane 212 is positioned between the anode 204
and the anode electrolyte 203 such that anions may migrate from the salt
solution 211 to the anode electrolyte 203 through the anion exchange
membrane 213; however, anions are prevented from contacting the anode 204
by the second cation exchange membrane 212 adjacent to the anode 204. It
is to be understood that there may be more than one anion exchange
membranes and cation exchange membranes in the system depending on the
desired configuration of the electrochemical cell.

[0135] In some embodiments, the system is configurable to migrate anions,
e.g., chloride ions, from the salt solution 211 to the anode electrolyte
203 through the anion exchange membrane 213; migrate cations, e.g.,
sodium ions from the salt solution 211 to the cathode electrolyte 202
through the first cation exchange membrane 206; migrate protons from the
anode 204 to the anode electrolyte 203; and migrate hydroxide ions from
the cathode 201 to the cathode electrolyte 202. In some embodiments, the
system may be configured to contact the bicarbonate solution with the
cathode electrolyte inside the cathode chamber (FIG. 5A) or outside the
cathode chamber (FIG. 5B). Thus, in some embodiments, the system may be
configured to produce sodium hydroxide and/or sodium bicarbonate and/or
sodium carbonate in the cathode electrolyte 202; and produce an acid
e.g., hydrochloric acid 210 in the anode electrolyte 203.

[0136] In some embodiments for FIGS. 5A and 5B, on applying the voltage
across the anode and cathode, the system can be configured to produce
hydroxide ions and hydrogen gas at the cathode 201; migrate hydroxide
ions from the cathode into the cathode electrolyte 202; migrate cations
from the salt solution 211 to the cathode electrolyte 202 through the
first cation exchange membrane 206; migrate chloride ions from the salt
solution 211 to the anode electrolyte 203 through the anion exchange
membrane 213; and migrate protons from the anode 204 to the anode
electrolyte 203. Hence, depending on the salt solution 211 used, the
system can be configured to produce an alkaline solution, e.g., sodium
hydroxide in the cathode electrolyte. The first cation exchange membrane
206 may block the migration of anions from the cathode electrolyte 202 to
the salt solution 211, causing the hydroxide ions to accumulate in the
cathode electrolyte. The anion exchange membrane 213 may block the
migration of cations, e.g., protons from the anode electrolyte 203 to the
salt solution 211 causing the protons to accumulate in the anode
electrolyte. With reference to FIGS. 5A and 5B, the system in some
embodiments includes a second cation exchange membrane 212, attached to
the anode 204, such that it separates the anode 204 from the anode
electrolyte 203. In this configuration, as the second cation exchange
membrane 212 is permeable to cations, protons formed at the anode will
migrate to the anode electrolyte as described herein; however, as the
second cation exchange membrane 212 is impermeable to anions, e.g.,
chloride ions, in the anode electrolyte will be blocked from migrating to
the anode 204, thereby avoiding interaction between the anode and the
anions that may interact with the anode, e.g., by corrosion.

[0137] In the system as illustrated in FIGS. 5A and 5B, with the voltage
across the anode and cathode, since the salt solution is separated from
the cathode electrolyte by the first cation exchange membrane 206,
cations in the salt solution, e.g., sodium ions, will migrate through the
first cation exchange membrane 206 to the cathode electrolyte 202, and
anions, e.g., chloride ions, will migrate to the anode electrolyte 203
through the anion exchange membrane 213. Consequently, in the system, as
illustrated in FIGS. 5A and 5B, an acid, e.g., hydrochloric acid 210 will
be produced in the anode electrolyte 203, and alkaline solution, e.g.,
sodium hydroxide will be produced in the cathode electrolyte. With the
migration of cations and anions from the salt solution, the system in
some embodiments can be configured to produce a partly de-ionized salt
solution from the salt solution 211. In some embodiments, this partially
de-ionized salt solution can be used as feed-water to a desalination
facility (not shown) where it can be further processed to produce
desalinated water as described in commonly assigned U.S. Patent
Application Publication no. US 2009/0001020, filed on Jun. 27, 2008,
herein incorporated by reference in its entirety. In some embodiments,
the solution can be used in industrial and agricultural applications
where its salinity is acceptable.

[0138] With the migration of cations and anions from the salt solution,
the system in some embodiments can be configured to produce a partly or
fully de-ionized salt solution from the salt solution 211. In some
embodiments, this partially de-ionized salt solution can be used as
feed-water to a desalination facility (not shown) where it can be further
processed to produce desalinated water as described in commonly assigned
U.S. Patent Application Publication no. US 2009/0001020, filed on Jun.
27, 2008, herein incorporated by reference in its entirety. In some
embodiments, the solution can be used in industrial and agricultural
applications where its salinity is acceptable. In some embodiments, the
partly de-ionized salt solution may be circulated to the anode
electrolyte 203 which may then produce a partly or fully depleted or
de-ionized salt solution for further processing, as described herein.
Such recirculation of the partly de-ionized salt solution to the anode
electrolyte 203 may be carried out in any of the electrochemical cell
described herein or any electrochemical cell that is within the scope of
the invention.

[0139] With reference to figures described herein, the system is
configured to direct hydrogen gas from the cathode to the anode. It is to
be understood that the systems where the hydrogen gas is not directed
towards the anode are well within the scope of the invention. In some
embodiments, the voltage across the anode and the cathode can be adjusted
such that gas may form at the anode, e.g., oxygen or chlorine gas, while
hydroxide ions and hydrogen gas is generated at the cathode. In such
embodiments, hydrogen gas is not supplied to the anode. However, in this
embodiment, the voltage across the anode and the cathode may generally be
higher compared to the embodiments where a gas does not form at the anode
and the hydrogen gas is directed from the cathode to the anode.

[0140] The systems provided herein may include a hydrogen gas supply
system configured to provide hydrogen gas to the anode. In some
embodiments, the hydrogen may be obtained from the cathode and/or
obtained from an external source, e.g., a commercial hydrogen gas
supplier e.g., at start-up of operations when the hydrogen supply from
the cathode is insufficient. In some embodiments, the hydrogen delivery
system is configured to deliver gas to the anode where oxidation of the
gas is catalyzed to protons and electrons. In some embodiments, the
hydrogen gas is oxidized to protons and electrons; un-reacted hydrogen
gas in the system may be recovered and re-circulated to the anode. The
hydrogen delivery system includes any means suitable for directing the
hydrogen gas from the cathode or from the external source to the anode.
Such means for directing the hydrogen gas from the cathode or from the
external source to the anode are well known in the art and include, but
not limited to, pipe, duct, conduit, and the like. In some embodiments,
the system or the hydrogen delivery system includes a duct that directs
the hydrogen gas from the cathode to the anode. It is to be understood
that the hydrogen gas may be directed to the anode from the bottom of the
cell, top of the cell or sideways. In some embodiments, the hydrogen gas
may be directed to the anode through multiple entry ports.

[0141] On applying a voltage across the anode and the cathode, protons
form at the anode from oxidation of hydrogen gas supplied to the anode,
while hydroxide ions and hydrogen gas form at the cathode electrolyte
from the reduction of water, as follows:

H2=2H++2e- (anode, oxidation reaction)

2H2O+2e-=H2+2OH- (cathode, reduction reaction)

[0142] Since protons are formed at the anode from hydrogen gas provided to
the anode; and since a gas such as oxygen does not form at the anode; and
since water in the cathode electrolyte forms hydroxide ions and hydrogen
gas at the cathode, the system can produce hydroxide ions in the cathode
electrolyte and protons in the anode electrolyte when a voltage is
applied across the anode and cathode. Further, in the systems provided
herein, since a gas does not form at the anode, the system produces
hydroxide ions in the cathode electrolyte and hydrogen gas at the cathode
and hydrogen ions at the anode when less than 3V is applied across the
anode and cathode, in contrast to the higher voltage that is required
when a gas is generated at the anode, e.g., chlorine or oxygen. For
example, in some embodiments, hydroxide ions, bicarbonate ions and/or
carbonate ion are produced in the cathode electrolyte when a voltage of
3V or less, 2.9V or less, 2.8V or less, 2.7V or less, 2.6V or less, 2.5V
or less, 2.4V or less, 2.3V or less, 2.2V or less, 2.1V or less, 2.0V or
less, 1.9V or less, 1.8V or less, 1.7V or less, 1.6V or less, 1.5V or
less, 1.4V or less, 1.3V or less, 1.2V or less, 1.1V or less, 1.0V or
less, 0.9V or less, 0.8V or less, 0.7V or less, 0.6V or less, 0.5V or
less, 0.4V or less, 0.3V or less, 0.2V or less, or 0.1V or less, or 0.05V
or less, or between 0.05V-4V, or between 0.05V-3V, or between 0.05V-2.5V,
or between 0.05V-2V, or between 0.05V-1.5V, or between 0.05V-1V, or
between 0.05V-0.5V, or between 0.05V-0.1V, or between 0.1V-3V, or between
0.1V-2.5V, or between 0.1V-2V, or between 0.1V-1.5V, or between 0.1V-1V,
or between 0.1V-0.5V, or between 0.5V-3V, or between 0.5V-2.5V, or
between 0.5V-2V, or between 0.5V-1.5V, or between 0.5V-1V, or between
1V-3V, or between 1V-2.5V, or between 1V-2V, or between 1V-1.5V, or
between 1.5V-3V, or between 1.5V-2.5V, or between 1.5V-2V, or between
2V-3V, or between 2V-2.5V, or 0.05V, or 0.1V, or 0.5V, or 1V, or 2V, or
3V, is applied across the anode and cathode.

[0143] In another embodiment, the voltage across the anode and cathode can
be adjusted such that gas is formed at the anode, e.g., oxygen or
chlorine, while hydroxide ions, carbonate ions and/or bicarbonate ions
are produced in the cathode electrolyte and hydrogen gas is generated at
the cathode. However, in this embodiment, hydrogen gas is not supplied to
the anode. As can be appreciated by one ordinarily skilled in the art, in
this embodiment, the voltage across the anode and cathode will be
generally higher compared to the embodiment when a gas does not form at
the anode.

[0144] In some embodiments, the bicarbonate solution, when contacted with
the cathode electrolyte inside the cathode chamber, reacts with the
hydroxide ions and produces water and carbonate ions, depending on the pH
of the cathode electrolyte. The addition of the bicarbonate solution to
the cathode electrolyte may lower the pH of the cathode electrolyte.
Thus, depending on the degree of alkalinity desired in the cathode
electrolyte, the pH of the cathode electrolyte may be adjusted and in
some embodiments is maintained between and 7 and 14 or greater; or
between 7 and 13; or between 7 and 12; or between 7 and 11; or between 7
and 10; or between 7 and 9; or between 7 and 8; or between 8 and 14 or
greater; or between 8 and 13; or between 8 and 12; or between 8 and 11;
or between 8 and 10; or between 8 and 9; or between 9 and 14 or greater;
or between 9 and 13; or between 9 and 12; or between 9 and 11; or between
9 and 10; or between 10 and 14 or greater; or between 10 and 13; or
between 10 and 12; or between 10 and 11; or between 11 and 14 or greater;
or between 11 and 13; or between 11 and 12; or between 12 and 14 or
greater; or between 12 and 13; or between 13 and 14 or greater. In some
embodiments, the pH of the cathode electrolyte may be adjusted to any
value between 7 and 14 or greater, including a pH 7.0, 7.5, 8.0, 8.5.
9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, and/or
greater.

[0145] Similarly, in some embodiments of the system, the pH of the anode
electrolyte is adjusted and is maintained between 0-7; or between 0-6; or
between 0-5; or between 0-4; or between 0-3; or between 0-2; or between
0-1, by regulating the concentration of hydrogen ions that migrate into
the anode electrolyte from oxidation of hydrogen gas at the anode, and/or
the withdrawal and replenishment of anode electrolyte in the system. As
the voltage across the anode and cathode may be dependent on several
factors including the difference in pH between the anode electrolyte and
the cathode electrolyte (as can be determined by the Nernst equation well
known in the art), in some embodiments, the pH of the anode electrolyte
may be adjusted to a value between 0 and 7, including 0, 0.5, 1.0, 1.5,
2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7, depending on the
desired operating voltage across the anode and cathode. Thus, as can be
appreciated, in equivalent systems, where it is desired to reduce the
energy used and/or the voltage across the anode and cathode, e.g., as in
the chloralkali process, the bicarbonate solution can be added to the
cathode electrolyte as disclosed herein to achieve a desired pH
difference between the anode electrolyte and cathode electrolyte. Thus,
to the extent that such systems utilize the bicarbonate solution, these
equivalent systems are within the scope of the present invention.

[0146] The system may be configured to produce any desired pH difference
between the anode electrolyte and the cathode electrolyte by modulating
the pH of the anode electrolyte, the pH of the cathode electrolyte, the
concentration of sodium hydroxide in the cathode electrolyte, the
concentration of hydrochloric acid in the anode electrolyte, the amount
of hydrogen gas from the cathode to the anode, the withdrawal and
replenishment of the anode electrolyte, the withdrawal and replenishment
of the cathode electrolyte, and/or the amount of the bicarbonate solution
added to the cathode electrolyte. By modulating the pH difference between
the anode electrolyte and the cathode electrolyte, the operating voltage
across the anode and the cathode can be modulated. In some embodiments,
the system is configured to produce a pH difference of at least 4 pH
units; at least 5 pH units; at least 6 pH units; at least 7 pH units; at
least 8 pH units; at least 9 pH units; at least 10 pH units; at least 11
pH units; at least 12 pH units; at least 13 pH units; at least 14 pH
units; or between 4-12 pH units; or between 4-11 pH units; or between
4-10 pH units; or between 4-9 pH units; or between 4-8 pH units; or
between 4-7 pH units; or between 4-6 pH units; or between 4-5 pH units;
or between 3-12 pH units; or between 3-11 pH units; or between 3-10 pH
units; or between 3-9 pH units; or between 3-8 pH units; or between 3-7
pH units; or between 3-6 pH units; or between 3-5 pH units; or between
3-4 pH units; or between 5-12 pH units; or between 5-11 pH units; or
between 5-10 pH units; or between 5-9 pH units; or between 5-8 pH units;
or between 5-7 pH units; or between 5-6 pH units; or between 7-12 pH
units; or between 7-11 pH units; or between 7-10 pH units; or between 7-9
pH units; or between 7-8 pH units; or between 8-12 pH units; or between
8-11 pH units; or between 8-10 pH units; or between 8-9 pH units; or
between 9-12 pH units; or between 9-11 pH units; or between 9-10 pH
units; or between 10-12 pH units; or between 10-11 pH units; or between
11-12 pH units; between the anode electrolyte and the cathode
electrolyte. In some embodiments, the system is configured to produce a
pH difference of at least 4 pH units between the anode electrolyte and
the cathode electrolyte.

[0147] In some embodiments, the system is configured to produce the above
recited pH difference between the anode electrolyte and the cathode
electrolyte when a voltage of 3V or less, 2.9V or less, 2.8V or less,
2.7V or less, 2.6V or less, 2.5V or less, 2.4V or less, 2.3V or less,
2.2V or less, 2.1V or less, 2.0V or less, 1.9V or less, 1.8V or less,
1.7V or less, 1.6V or less, 1.5V or less, 1.4V or less, 1.3V or less,
1.2V or less, 1.1V or less, 1.0V or less, 0.9V or less, 0.8V or less,
0.7V or less, 0.6V or less, 0.5V or less, 0.4V or less, 0.3V or less,
0.2V or less, or 0.1V or less, or 0.05V or less, or between 0.05V-4V, or
between 0.05V-3V, or between 0.05V-2.5V, or between 0.05V-2V, or between
0.05V-1.5V, or between 0.05V-1V, or between 0.05V-0.5V, or between
0.05V-0.1V, or between 0.1V-3V, or between 0.1V-2.5V, or between 0.1V-2V,
or between 0.1V-1.5V, or between 0.1V-1V, or between 0.1V-0.5V, or
between 0.1V-0.05V, or between 0.5V-3V, or between 0.5V-2.5V, or between
0.5V-2V, or between 0.5V-1.5V, or between 0.5V-1V, or between 1V-3V, or
between 1V-2.5V, or between 1V-2V, or between 1V-1.5V, or between 2V-3V,
or between 2V-2.5V, or 0.05V, or 0.1V, or 0.5V, or 1V, or 2V, or 3V, is
applied between the anode and the cathode.

[0148] In some embodiments, the cathode electrolyte and/or the anode
electrolyte in the systems and methods provided herein include, but are
not limited to, saltwater or fresh water. The saltwater includes, but is
not limited to, seawater, brine, and/or brackish water. In some
embodiments, the cathode electrolyte in the systems and methods provided
herein include, but are not limited to, seawater, freshwater, brine,
brackish water, sodium hydroxide, or combination thereof. "Saltwater" is
employed in its conventional sense to refer to a number of different
types of aqueous fluids other than fresh water, where the term
"saltwater" includes, but is not limited to, brackish water, sea water
and brine (including, naturally occurring subterranean brines or
anthropogenic subterranean brines and man-made brines, e.g., geothermal
plant wastewaters, desalination waste waters, etc), as well as other
salines having a salinity that is greater than that of freshwater. Brine
is water saturated or nearly saturated with salt and has a salinity that
is 50 parts per million (ppm) or 50 ppt (parts per thousand) or greater.
Brackish water is water that is saltier than fresh water, but not as
salty as seawater, having a salinity ranging from 0.5 to 35 ppt. Seawater
is water from a sea or ocean and has a salinity ranging from 35 to 50
ppt. The saltwater source may be a naturally occurring source, such as a
sea, ocean, lake, swamp, estuary, lagoon, etc., or a man-made source. In
some embodiments, the cathode electrolyte and/or the anode electrolyte,
such as, saltwater includes water containing more than 1% chloride
content, such as, NaCl; or more than 10% NaCl; or more than 20% NaCl; or
more than 30% NaCl; or more than 40% NaCl; or more than 50% NaCl; or more
than 60% NaCl; or more than 70% NaCl; or more than 80% NaCl; or more than
90% NaCl; or between 1-99% NaCl; or between 1-95% NaCl; or between 1-90%
NaCl; or between 1-80% NaCl; or between 1-70% NaCl; or between 1-60%
NaCl; or between 1-50% NaCl; or between 1-40% NaCl; or between 1-30%
NaCl; or between 1-20% NaCl; or between 1-10% NaCl; or between 10-99%
NaCl; or between 10-95% NaCl; or between 10-90% NaCl; or between 10-80%
NaCl; or between 10-70% NaCl; or between 10-60% NaCl; or between 10-50%
NaCl; or between 10-40% NaCl; or between 10-30% NaCl; or between 10-20%
NaCl; or between 20-99% NaCl; or between 20-95% NaCl; or between 20-90%
NaCl; or between 20-80% NaCl; or between 20-70% NaCl; or between 20-60%
NaCl; or between 20-50% NaCl; or between 20-40% NaCl; or between 20-30%
NaCl; or between 30-99% NaCl; or between 30-95% NaCl; or between 30-90%
NaCl; or between 30-80% NaCl; or between 30-70% NaCl; or between 30-60%
NaCl; or between 30-50% NaCl; or between 30-40% NaCl; or between 40-99%
NaCl; or between 40-95% NaCl; or between 40-90% NaCl; or between 40-80%
NaCl; or between 40-70% NaCl; or between 40-60% NaCl; or between 40-50%
NaCl; or between 50-99% NaCl; or between 50-95% NaCl; or between 50-90%
NaCl; or between 50-80% NaCl; or between 50-70% NaCl; or between 50-60%
NaCl; or between 60-99% NaCl; or between 60-95% NaCl; or between 60-90%
NaCl; or between 60-80% NaCl; or between 60-70% NaCl; or between 70-99%
NaCl; or between 70-95% NaCl; or between 70-90% NaCl; or between 70-80%
NaCl; or between 80-99% NaCl; or between 80-95% NaCl; or between 80-90%
NaCl; or between 90-99% NaCl; or between 90-95% NaCl.

[0149] In some embodiments, the cathode electrolyte and/or the anode
electrolyte includes water containing more than 1% sulfate content or
between 1-100% sulfate, such as, sodium sulfate, potassium sulfate, and
the like; or more than 10% sulfate; or more than 20% sulfate; or more
than 30% sulfate; or more than 40% sulfate; or more than 50% sulfate; or
more than 60% sulfate; or more than 70% sulfate; or more than 80%
sulfate; or more than 90% sulfate; or between 1-99% sulfate; or between
1-95% sulfate; or between 1-90% sulfate; or between 1-80% sulfate; or
between 1-70% sulfate; or between 1-60% sulfate; or between 1-50%
sulfate; or between 1-40% sulfate; or between 1-30% sulfate; or between
1-20% sulfate; or between 1-10% sulfate; or between 10-99% sulfate; or
between 10-95% sulfate; or between 10-90% sulfate; or between 10-80%
sulfate; or between 10-70% sulfate; or between 10-60% sulfate; or between
10-50% sulfate; or between 10-40% sulfate; or between 10-30% sulfate; or
between 10-20% sulfate; or between 20-99% sulfate; or between 20-95%
sulfate; or between 20-90% sulfate; or between 20-80% sulfate; or between
20-70% sulfate; or between 20-60% sulfate; or between 20-50% sulfate; or
between 20-40% sulfate; or between 20-30% sulfate; or between 30-99%
sulfate; or between 30-95% sulfate; or between 30-90% sulfate; or between
30-80% sulfate; or between 30-70% sulfate; or between 30-60% sulfate; or
between 30-50% sulfate; or between 30-40% sulfate; or between 40-99%
sulfate; or between 40-95% sulfate; or between 40-90% sulfate; or between
40-80% sulfate; or between 40-70% sulfate; or between 40-60% sulfate; or
between 40-50% sulfate; or between 50-99% sulfate; or between 50-95%
sulfate; or between 50-90% sulfate; or between 50-80% sulfate; or between
50-70% sulfate; or between 50-60% sulfate; or between 60-99% sulfate; or
between 60-95% sulfate; or between 60-90% sulfate; or between 60-80%
sulfate; or between 60-70% sulfate; or between 70-99% sulfate; or between
70-95% sulfate; or between 70-90% sulfate; or between 70-80% sulfate; or
between 80-99% sulfate; or between 80-95% sulfate; or between 80-90%
sulfate; or between 90-99% sulfate; or between 90-95% sulfate.

[0150] In some embodiments, the cathode electrolyte, such as, saltwater,
fresh water, and/or sodium hydroxide do not include divalent cations. As
used herein, the divalent cations include alkaline earth metal ions, such
as but not limited to, calcium, magnesium, barium, strontium, radium,
etc. In some embodiments, the cathode electrolyte, such as, saltwater,
fresh water, and/or sodium hydroxide include less than 1% w/w divalent
cations. Examples of salt water include, but not limited to, seawater,
freshwater including sodium chloride, brine, or brackish water. In some
embodiments, the cathode electrolyte, such as, seawater, freshwater,
brine, brackish water, and/or sodium hydroxide include less than 1% w/w
divalent cations. In some embodiments, the cathode electrolyte, such as,
seawater, freshwater, brine, brackish water, and/or sodium hydroxide
include divalent cations including, but not limited to, calcium,
magnesium, and combination thereof. In some embodiments, the cathode
electrolyte, such as, seawater, freshwater, brine, brackish water, and/or
sodium hydroxide include less than 1% w/w divalent cations including, but
not limited to, calcium, magnesium, and combination thereof. In some
embodiments, the cathode electrolyte, such as, seawater, freshwater,
brine, brackish water, and/or sodium hydroxide include less than 1% w/w;
or less than 5% w/w; or less than 10% w/w; or less than 15% w/w; or less
than 20% w/w; or less than 25% w/w; or less than 30% w/w; or less than
40% w/w; or less than 50% w/w; or less than 60% w/w; or less than 70%
w/w; or less than 80% w/w; or less than 90% w/w; or less than 95% w/w; or
between 0.05-1% w/w; or between 0.5-1% w/w; or between 0.5-5% w/w; or
between 0.5-10% w/w; or between 0.5-20% w/w; or between 0.5-30% w/w; or
between 0.5-40% w/w; or between 0.5-50% w/w; or between 0.5-60% w/w; or
between 0.5-70% w/w; or between 0.5-80% w/w; or between 0.5-90% w/w; or
between 5-8% w/w; or between 5-10% w/w; or between 5-20% w/w; or between
5-30% w/w; or between 5-40% w/w; or between 5-50% w/w; or between 5-60%
w/w; or between 5-70% w/w; or between 5-80% w/w; or between 5-90% w/w; or
between 10-20% w/w; or between 10-30% w/w; or between 10-40% w/w; or
between 10-50% w/w; or between 10-60% w/w; or between 10-70% w/w; or
between 10-80% w/w; or between 10-90% w/w; or between 30-40% w/w; or
between 30-50% w/w; or between 30-60% w/w; or between 30-70% w/w; or
between 30-80% w/w; or between 30-90% w/w; or between 50-60% w/w; or
between 50-70% w/w; or between 50-80% w/w; or between 50-90% w/w; or
between 75-80% w/w; or between 75-90% w/w; or between 80-90% w/w; or
between 90-95% w/w; of divalent cations including, but not limited to,
calcium, magnesium, and combination thereof.

[0151] In some embodiments, the cathode electrolyte includes, but not
limited to, sodium hydroxide, sodium bicarbonate, sodium carbonate, or
combination thereof. In some embodiments, the cathode electrolyte
includes, but not limited to, sodium hydroxide. In some embodiments, the
cathode electrolyte includes, but not limited to, sodium hydroxide,
divalent cations, or combination thereof. In some embodiments, the
cathode electrolyte includes, but not limited to, sodium hydroxide,
sodium bicarbonate, sodium carbonate, divalent cations, or combination
thereof. In some embodiments, the cathode electrolyte includes, but not
limited to, sodium hydroxide, calcium bicarbonate, calcium carbonate,
magnesium bicarbonate, magnesium carbonate, calcium magnesium carbonate,
or combination thereof. In some embodiments, the cathode electrolyte
includes, but not limited to, saltwater, sodium hydroxide, bicarbonate
brine solution, or combination thereof. In some embodiments, the cathode
electrolyte includes, but not limited to, saltwater and sodium hydroxide.
In some embodiments, the cathode electrolyte includes, but not limited
to, fresh water and sodium hydroxide. In some embodiments, the cathode
electrolyte includes, but not limited to, fresh water, sodium hydroxide,
sodium bicarbonate, sodium carbonate, divalent cations, or combination
thereof.

[0152] In some embodiments, the anode electrolyte includes, but not
limited to, fresh water and hydrochloric acid. In some embodiments, the
anode electrolyte includes, but not limited to, saltwater and
hydrochloric acid. In some embodiments, the anode electrolyte includes
hydrochloric acid.

[0153] As is illustrated in FIGS. 2A, 2B, 3A, and 3B, in some embodiments,
the anode electrolyte includes saltwater solution and hydrochloric acid
and the cathode electrolyte includes hydroxide. As is illustrated in
FIGS. 4A and 4B, in some embodiments, the cathode electrolyte includes
saltwater solution and hydroxide and the anode electrolyte includes
hydrochloric acid. As is illustrated in FIGS. 5A and 5B, in some
embodiments, the cathode electrolyte includes hydroxide and the anode
electrolyte includes hydrochloric acid. In some embodiments, the depleted
saltwater from the cell may be circulated back to the anode electrolyte.
In some embodiments, the cathode electrolyte includes 1-90%; 1-50%; or
1-40%; or 1-30%; or 1-15%; or 1-20%; or 1-10%; or 5-90%; or 5-50%; or
5-40%; or 5-30%; or 5-20%; or 5-10%; or 10-90%; or 10-50%; or 10-40%; or
10-30%; or 10-20%; or 15-20%; or 15-30%; or 20-30%, of the sodium
hydroxide solution. In some embodiments, the anode electrolyte includes
0-5 M hydrochloric acid solution; or 0-4.5M; or 0-4M; or 0-3.5M; or 0-3M;
or 0-2.5M; or 0-2M; or 0-1.5M; or 0-1M; or 1-5M; or 1-4.5M; or 1-4M; or
1-3.5M; or 1-3M; or 1-2.5M; or 1-2M; or 1-1.5M; or 2-5M; or 2-4.5M; or
2-4M; or 2-3.5M; or 2-3M; or 2-2.5M; or 3-5M; or 3-4.5M; or 3-4M; or
3-3.5M; or 4-5M; or 4.5-5M. In some embodiments, the anode does not form
an oxygen gas. In some embodiments, the anode does not form a chlorine
gas.

[0154] In some embodiments, the cathode electrolyte does not include
carbon dioxide gas. In some embodiments, no carbon dioxide is dissolved
into the cathode electrolyte of the electrochemical cell. Although carbon
dioxide may be present in ordinary ambient air, in view of its very low
concentration, ambient carbon dioxide will not provide sufficient carbon
dioxide to achieve the formation of the bicarbonate and/or carbonate in
the cathode electrolyte as is obtained when bicarbonate solution is
contacted with the cathode electrolyte inside the cathode chamber. In
some embodiments of the system and method, the pressure inside the
electrochemical system may be greater than the ambient atmospheric
pressure in the ambient air and hence ambient carbon dioxide may
typically be prevented from infiltrating into the cathode electrolyte.

[0155] In some embodiments, the system is configured to produce hydroxide
ions at the cathode without forming a gas at the anode on applying a
voltage across the anode and the cathode. In some embodiments, the system
is configured to produce hydroxide ions in the cathode electrolyte and an
acid in the anode electrolyte on applying a voltage across the anode and
the cathode. In some embodiments, the system is configured to produce
acid, such as, but not limited to, hydrochloric acid or sulfuric acid in
the anode electrolyte.

[0156] In some embodiments, the cathode electrolyte and the anode
electrolyte are separated in part or in full by an ion exchange membrane.
In some embodiments, the ion exchange membrane is an anion exchange
membrane or a cation exchange membrane. In some embodiments, the cation
exchange membranes in the electrochemical cell, as disclosed herein, are
conventional and are available from, for example, Asahi Kasei of Tokyo,
Japan; or from Membrane International of Glen Rock, N.J., or DuPont, in
the USA. Examples of cationic exchange membranes include, but not limited
to, cationic membrane consisting of a perfluorinated polymer containing
anionic groups, for example sulphonic and/or carboxylic groups. However,
it may be appreciated that in some embodiments, depending on the need to
restrict or allow migration of a specific cation or an anion species
between the electrolytes, a cation exchange membrane that is more
restrictive and thus allows migration of one species of cations while
restricting the migration of another species of cations may be used as,
e.g., a cation exchange membrane that allows migration of sodium ions
into the cathode electrolyte from the anode electrolyte while restricting
migration of hydrogen ions from the anode electrolyte into the cathode
electrolyte, may be used. Similarly, it may be appreciated that in some
embodiments, depending on the need to restrict or allow migration of a
specific anion species between the electrolytes, an anion exchange
membrane that is more restrictive and thus allows migration of one
species of anions while restricting the migration of another species of
anions may be used as, e.g., an anion exchange membrane that allows
migration of chloride ions into the anode electrolyte from the cathode
electrolyte while restricting migration of hydroxide ions from the
cathode electrolyte into the anode electrolyte, may be used. Such
restrictive cation and/or anion exchange membranes are commercially
available and can be selected by one ordinarily skilled in the art.

[0157] In some embodiments, there is provided a system comprising one or
more anion exchange membrane, and cation exchange membranes located
between the anode and the cathode. In some embodiments, the membranes
should be selected such that they can function in an acidic and/or basic
electrolytic solution as appropriate. Other desirable characteristics of
the membranes include high ion selectivity, low ionic resistance, high
burst strength, and high stability in an acidic electrolytic solution in
a temperature range of 0° C. to 100° C. or higher, or a
alkaline solution in similar temperature range may be used. In some
embodiments, a membrane that is stable in the range of 0° C. to
90° C.; or 0° C. to 80° C.; or 0° C. to
70° C.; or 0° C. to 60° C.; or 0° C. to
50° C.; or 0° C. to 40° C., or 0° C. to
30° C., or 0° C. to 20° C., or 0° C. to
10° C., or higher may be used. In some embodiments, a membrane
that is stable in the range of 0° C. to 90° C.; or
0° C. to 80° C.; or 0° C. to 70° C.; or
0° C. to 60° C.; or 0° C. to 50° C.; or
0° C. to 40° C., but unstable at higher temperature, may be
used. For other embodiments, it may be useful to utilize an ion-specific
ion exchange membranes that allows migration of one type of cation but
not another; or migration of one type of anion and not another, to
achieve a desired product or products in an electrolyte. In some
embodiments, the membrane may be stable and functional for a desirable
length of time in the system, e.g., several days, weeks or months or
years at temperatures in the range of 0° C. to 90° C.; or
0° C. to 80° C.; or 0° C. to 70° C.; or
0° C. to 60° C.; or 0° C. to 50° C.; or
0° C. to 40° C.; or 0° C. to 30° C.; or
0° C. to 20° C.; or 0° C. to 10° C., and
higher and/or lower. In some embodiments, for example, the membranes may
be stable and functional for at least 1 day, at least 5 days, 10 days, 15
days, 20 days, 100 days, 1000 days, 5-10 years, or more in electrolyte
temperatures at 100° C., 90° C., 80° C., 70°
C., 60° C., 50° C., 40° C., 30° C.,
20° C., 10° C., 5° C. and more or less.

[0158] The ohmic resistance of the membranes may affect the voltage drop
across the anode and cathode, e.g., as the ohmic resistance of the
membranes increase, the voltage across the anode and cathode may
increase, and vice versa. Membranes that can be used include, but are not
limited to, membranes with relatively low ohmic resistance and relatively
high ionic mobility; and membranes with relatively high hydration
characteristics that increase with temperatures, and thus decreasing the
ohmic resistance. By selecting currently available membranes with lower
ohmic resistance, the voltage drop across the anode and cathode at a
specified temperature can be lowered.

[0159] Scattered through currently available membranes may be ionic
channels including acid groups. These ionic channels may extend from the
internal surface of the matrix to the external surface and the acid
groups may readily bind water in a reversible reaction as
water-of-hydration. This binding of water as water-of-hydration may
follow first order reaction kinetics, such that the rate of reaction is
proportional to temperature. Consequently, currently available membranes
can be selected to provide a relatively low ohmic and ionic resistance
while providing for improved strength and resistance in the system for a
range of operating temperatures.

[0160] In some embodiments, the anode in the electrochemical cell is
configured to oxidize hydrogen gas (a hydrogen oxidizing anode) to
produce hydrogen ions. In some embodiments, the systems provided herein
may comprise a gas diffusion anode. In some embodiments, the anode and
the second cation exchange membrane may include an integral gas diffusion
anode that is commercially available, or can be fabricated as described
for example in co-pending and commonly assigned International Patent
Application Publication no. WO 2010/093716, titled "Low-voltage alkaline
production using hydrogen and electrocatalytic electrodes", filed Feb.
10, 2010, herein fully incorporated by reference. It is to be understood
that the gas diffusion anode is illustrated as an example only and any
conventional anode that can be configured to oxidize hydrogen gas (a
hydrogen oxidizing anode) to produce hydrogen, can be utilized.

[0161] In some embodiments, e.g. as illustrated in FIGS. 3A and 3B, the
anode may be a gas diffusion anode including an ion exchange membrane,
e.g., a cation exchange membrane 212 that contacts the second side 604 of
the anode. In such embodiments, the ion exchange membrane can be used to
allow or prevent migration of ions to or from the anode. Thus, for
example, with reference to FIG. 3A, when protons are generated at the
anode, a cation exchange membrane may be used to facilitate the migration
of the protons from the anode and/or block the migration of ions, e.g.,
cations to the substrate. In the some embodiments, the ion exchange
membrane may be selected to preferentially allow passage of one type of
cation, e.g., hydrogen ions, while preventing the passage of another type
of ions, e.g., sodium ions.

[0162] In some embodiments, the systems provided herein include the
saltwater from terrestrial brine. In some embodiments, the depleted
saltwater withdrawn from the electrochemical cells is replenished with
sodium chloride and re-circulated back in the electrochemical cell. In
some embodiments, the depleted saltwater withdrawn from the
electrochemical cell is re-circulated to the anode chamber of the
electrochemical cell.

[0163] In some embodiments of the electrochemical cells herein, the system
is configured to produce carbonate ions by a reaction of the bicarbonate
ions from the bicarbonate solution with sodium hydroxide from the cathode
electrolyte. The contacting of the bicarbonate solution with the cathode
electrolyte may be outside the cathode chamber and/or inside the cathode
chamber. In some embodiments, the bicarbonate solution may be contacted
with the cathode electrolyte inside the cathode chamber and after
withdrawing or recovering the cathode electrolyte containing hydroxide
and/or bicarbonate and/or carbonate, the cathode electrolyte may be again
contacted with the bicarbonate solution outside the cathode chamber to
react any un-reacted hydroxide with the bicarbonate to produce the
carbonate.

[0164] The degree of conversion of bicarbonate to carbonate in the
presence of sodium hydroxide may be dependent on the concentration of the
sodium hydroxide produced by the cathode; the concentration of the
bicarbonate solution reacted with the sodium hydroxide; and/or pH of the
cathode electrolyte. The amount of bicarbonate converted to the carbonate
in the presence of sodium hydroxide, outside the cathode chamber and/or
inside the cathode chamber, may be 100%; or more than 90%; or more than
80%; or more than 70%; or more than 60%; or more than 50%; or more than
40%; or more than 30%; or more than 20%; or more than 10%; or more than
5%; or more than 1%; or between 1-99%; or between 1-90%; or between
1-80%; or between 1-70%; or between 1-60%; or between 1-50%; or between
1-40%; or between 1-30%; or between 1-20%; or between 1-10%; or between
5-99%; or between 5-90%; or between 5-80%; or between 5-70%; or between
5-60%; or between 5-50%; or between 5-40%; or between 5-30%; or between
5-20%; or between 5-10%; or between 10-99%; or between 10-90%; or between
10-80%; or between 10-70%; or between 10-60%; or between 10-50%; or
between 10-40%; or between 10-30%; or between 10-20%; or between 20-99%;
or between 20-90%; or between 20-80%; or between 20-70%; or between
20-60%; or between 20-50%; or between 20-40%; or between 20-30%; or
between 30-99%; or between 30-90%; or between 30-80%; or between 30-70%;
or between 30-60%; or between 30-50%; or between 30-40%; or between
40-99%; or between 40-90%; or between 40-80%; or between 40-70%; or
between 40-60%; or between 40-50%; or between 50-99%; or between 50-90%;
or between 50-80%; or between 50-70%; or between 50-60%; or between
60-99%; or between 60-90%; or between 60-80%; or between 60-70%; or
between 70-99%; or between 70-90%; or between 70-80%; or between 80-99%;
or between 80-90%; or between 90-100%; or between 90-99%.

[0165] The system in some embodiments includes a cathode electrolyte
circulating system adapted for withdrawing and circulating cathode
electrolyte in the system. In one embodiment, the cathode electrolyte
circulating system includes a bicarbonate solution contactor outside the
cathode chamber that is adapted for contacting the bicarbonate solution
with the circulating cathode electrolyte, and for re-circulating the
electrolyte in the system. As can be appreciated, since the pH of the
cathode electrolyte can be adjusted by withdrawing and/or circulating
cathode electrolyte/bicarbonate solution from the system, the pH of the
cathode electrolyte compartment can be regulated by regulating an amount
of cathode electrolyte removed from the system, passed through the
bicarbonate solution contactor, and/or re-circulated back into the
cathode chamber.

[0166] In some embodiments, the systems provided herein include a contact
system configured to contact the bicarbonate solution to the cathode
electrolyte. The system or the contact system includes any means suitable
for contacting the bicarbonate solution with the cathode electrolyte
inside and/or outside the cathode chamber. Such means for directing the
bicarbonate solution to the cathode electrolyte inside a cathode chamber
are well known in the art and include, but not limited to, injection,
pipe, duct, conduit, and the like. In some embodiments, the system or the
contact system in the system includes a duct or a conduit that directs
the bicarbonate solution to the cathode electrolyte inside a cathode
chamber. It is to be understood that when the bicarbonate solution is
contacted with the cathode electrolyte inside the cathode chamber, the
bicarbonate solution may be injected to the cathode electrolyte from the
bottom of the cell, top of the cell, from the side inlet in the cell,
and/or from a combination of such entry ports depending on the amount of
bicarbonate solution desired in the cathode chamber. The amount of
bicarbonate solution inside the cathode chamber may be dependent on the
flow rate of the solution, desired pH of the cathode electrolyte, and/or
size of the cell. Such optimization of the amount of the bicarbonate
solution is well within the scope of the invention.

[0167] For the systems where the bicarbonate solution 205 is contacted
with the cathode electrolyte 202 outside the cathode chamber, the sodium
hydroxide containing cathode electrolyte may be withdrawn from the
cathode chamber and may be added to a contact system configured to
contact the bicarbonate solution with the cathode electrolyte. Such
contact system can be a container, pipe, duct, tank, conduit, or the
like. For example, the container may have an input for the bicarbonate
solution such as a pipe or conduit, etc. or a pipeline in communication
with a subterranean brine. The container may also be in fluid
communication with a reactor where the bicarbonate solution may be
produced, modified, and/or stored. The contact system for contacting the
bicarbonate solution with the cathode electrolyte outside the cathode
chamber may be equipped with inputs for other reagents for controlling
the pH, stirrers, temperature sensor, and the like.

[0168] In some embodiments, the source of the bicarbonate solution may be
a tanks or series of tanks containing the bicarbonate solution which is
then connected to the input for the bicarbonate solution for contacting
with the cathode electrolyte inside the cathode chamber and/or outside
the cathode chamber.

[0169] The methods and systems of the invention may also include producing
one or more bore holes (i.e., well bore) in the subterranean formation to
connect the subterranean brine to the system of the invention, such as,
to connect to the input for the bicarbonate brine or the bicarbonate
solution. One or more bore holes can be produced in the subterranean
formation by employing any suitable protocol. For instance, bore holes
may be produced using conventional excavation drilling techniques, e.g.,
particle jet drilling, rotary mechanical drilling, rotary blasthole
drilling, hole openers, rock reamers, flycutters, turbine-motor drilling,
thermal spallation drilling, high power pulse laser drilling or any
combination thereof. The bore holes may be drilled to any depth as
desired, depending upon the thickness of the walls and porosity of the
subterranean formation. In some embodiments, the bore holes may extend to
a depth of 1 meter or deeper into the subterranean formation, such as 5
meters or deeper into the subterranean formation, such as 10 meters or
deeper into the subterranean formation, such as 20 meters or deeper into
the subterranean formation, such as 30 meters or deeper into the
subterranean formation, such as 40 meters or deeper into the subterranean
formation, such as 50 meters or deeper into the subterranean formation,
such as 75 meters or deeper into the subterranean formation, including
100 meters or 200 m or 300 m or 500 m deeper into the subterranean
formation. The diameter of the bore hole may also vary, depending upon
the nature and the porosity of the subterranean formation. In some
embodiments, the diameter of the bore hole ranges, e.g., from 5 to 100
cm, such as 10 to 90 cm, such as 10 to 90 cm, such as 20 to 80 cm, such
as 25 to 75 cm, and including 30 to 50 cm.

[0170] After producing one or more bore holes in the subterranean
formation, methods of the invention may also include inserting one or
more conduits into the bore hole. The conduit includes a tube, pipeline
or an analogous structure configured to convey a gas or liquid from one
location to another. Conduits of the invention may vary in shape, where
the cross-section of the conduit may be circular, rectangular, oblong,
square, etc. The diameter of the conduit may also vary, depending on the
size of the bore hole as well as the nature of the composition (e.g.,
viscosity), ranging from 5 to 100 cm, such as 10 to 90 cm, such as 10 to
90 cm, such as 20 to 80 cm, such as 25 to 75 cm, and including 30 to 50
cm. Depending on the depth of the subterranean formation, the wall
thicknesses of the conduit may vary, ranging in some embodiments from 0.5
to 25 cm or thicker, such as 1 to 15 cm or thicker, such as 1 to 10 cm or
thicker, including 1 to 5 cm or thicker. In some embodiments, conduits
may be designed to support high internal pressure from the flow of the
brine composition. In other embodiments, the conduit may be designed to
support high external loadings (e.g., external hydrostatic pressures,
earth loads, etc.). Conduits may be inserted to any depth into the
subterranean formation, as desired, e.g., to a depth of 0.5 meter or
deeper into the subterranean formation, such as 1 meters or deeper into
the subterranean formation, such as 2 meters or deeper into the
subterranean formation, such as 3 meters or deeper into the subterranean
formation, such as 4 meters or deeper into the subterranean formation,
such as 5 meters or deeper into the subterranean formation, including 10
meters or 100 meters, or 200 meters or 300 meters deeper into the
subterranean formation. In some embodiments, conduits of the invention
are two-way delivery units such that a single conduit may be employed to
both introduce a fluid composition into the subterranean formation as
well as withdraw a fluid composition from within the subterranean brine.
For example, in some instances a conduit may be employed to introduce
water into the subterranean formation. In some embodiments, the same
conduit may be employed to withdraw the bicarbonate brine from within the
subterranean formation at a same time or later time. In other words,
conduits may be configured to both convey a fluid composition into the
subterranean formation as well as withdraw a fluid composition from
within the subterranean formation.

[0171] Brines disposed within the subterranean formation may be removed by
any convenient protocol, such as, but not limited to, employing an
oil-field pump, down-well turbine motor pump, rotary lobe pump, hydraulic
pump, fluid transfer pump, geothermal well pump, a water-submersible
vacuum pump, or surface-located brine pump, among other protocols. It is
to be understood that the above recited methods and systems to collect a
subterranean brine may be used for some embodiments of the invention
where a subterranean carbonate brine, or an alkaline brine, or a hard
brine, or an alkaline hard brine is desired. Brine disposed within the
subterranean formation may be used in any methods of this invention, for
example, as a source of alkalinity, source of carbonate brine, source of
bicarbonate brine, source of cations, such as, divalent cations, and/or
combinations thereof.

[0172] In some embodiments, the bicarbonate solution is contacted with the
cathode electrolyte, with the flow rate of greater than 1 mL/min; or
greater than 10 mL/min; or greater than 25 mL/min; or greater than 50
mL/min; or greater than 100 mL/min; or from 1 mL/min to 100 L/min; or
from 1 mL/min to 75 L/min; or from 1 mL/min to 50 L/min; or from 1 mL/min
to 40 L/min; or from 1 mL/min to 30 L/min; or from 1 mL/min to 20 L/min;
or from 1 mL/min to 10 L/min; or from 1 mL/min to 5 L/min; or from 5
mL/min to 100 L/min; or from 5 mL/min to 50 L/min; or from 5 mL/min to 40
L/min; or from 5 mL/min to 30 L/min; or from 5 mL/min to 20 L/min; or
from 5 mL/min to 10 L/min; or from 10 mL/min to 100 L/min; or from 10
mL/min to 50 L/min; or from 10 mL/min to 40 L/min; or from 10 mL/min to
30 L/min; or from 10 mL/min to 20 L/min; or from 10 mL/min to 15 L/min;
or from 20 mL/min to 100 L/min; or from 20 mL/min to 50 L/min; or from 20
mL/min to 40 L/min; or from 20 mL/min to 30 L/min; or from 30 mL/min to
100 L/min; or from 30 mL/min to 50 L/min; or from 30 mL/min to 40 L/min;
or from 30 mL/min to 35 L/min; or from 40 mL/min to 100 L/min; or from 40
mL/min to 50 L/min; or from 40 mL/min to 45 L/min; or from 50 mL/min to
100 L/min; or from 50 mL/min to 75 L/min. The concentration of the
bicarbonate solution that is contacted with the cathode electrolyte
inside and/or outside the cathode chamber is described below.

[0173] In some embodiments, the systems of the invention may include a
heat exchanger to collect and utilize excess thermal energy from
subterranean brines. The heat exchanger may be an open loop or closed
loop configuration to collect heat from the brine. Thermal energy may be
converted to electrical energy using a steam generator or any device
known in the art for generating electrical energy from an aqueous
geothermal source. Thermal energy may be used to run the electrochemical
process at a desired temperature, dry the precipitate or the compositions
provided herein.

[0174] In some embodiments, the cathode and the anode may be operatively
connected to an off-peak electrical power-supply system that supplies
off-peak voltage to the electrodes. Since the cost of off-peak power is
lower than the cost of power supplied during peak power-supply times, the
system can utilize off-peak power to produce an alkaline solution in the
cathode electrolyte at a relatively lower cost.

[0175] FIG. 6 illustrates a flow diagram 600 for some embodiments where
the electrochemical cell is integrated with other processes to recycle
the spent solutions, thereby reducing the overall energy consumption of
the process. In some embodiments, the alkaline solution produced by the
electrochemical cell 601 may be contacted with the bicarbonate solution
602 inside the cathode chamber and/or outside the cathode chamber to
produce a bicarbonate/carbonate ion solution. The bicarbonate/carbonate
ion solution or substantially carbonate ion solution 603 may be then
treated with the divalent cations, e.g., calcium, magnesium, or
combination thereof, to precipitate the bicarbonate and/or carbonate,
e.g., calcium carbonate, magnesium carbonate, calcium bicarbonate,
magnesium bicarbonate, calcium magnesium carbonate, or combination
thereof. The calcium carbonate, magnesium carbonate, calcium bicarbonate,
magnesium bicarbonate, calcium magnesium carbonate, or combination
thereof, form cementitous compositions. The sodium chloride or the sodium
sulfate solution withdrawn from the electrochemical cell 601 may
optionally be concentrated in the concentrator 604 before being injected
back into the electrochemical cell 601. The sodium chloride may be
separated from hydrochloric acid or sodium sulfate may be separated from
the sulfuric acid after being removed from the electrochemical cell. The
hydrochloric acid or the sulfuric acid produced by the electrochemical
cell 601 may be subjected to a mineral dissolution system 605 which may
be configured to dissolve minerals 606, such as mafic and/or ultramafic
minerals, e.g., serpentine, olivine, etc. and produce a mineral solution
comprising divalent cations, e.g., calcium and/or magnesium and/or
silica, etc. The mineral solution may then be filtered via nano
filtration system 607 to separate the divalent cations, such as calcium,
magnesium, silica, etc. from sodium chloride and HCl or from sodium
sulfate and sulfuric acid. The divalent cations may then be treated with
the bicarbonate/carbonate solution 603 to form carbonate compositions,
such as, calcium carbonate, magnesium carbonate, calcium bicarbonate,
magnesium bicarbonate, calcium magnesium carbonate, or combination
thereof. The filtrate containing the sodium chloride and HCl or from
sodium sulfate and sulfuric acid may then be subjected to reverse osmosis
system 608 to concentrate the sodium chloride or sodium sulfate solution
before injecting it back into the electrochemical cell 601. It is to be
understood that FIG. 6 is for illustration purposes only and does not in
any way limit the scope of the invention. Some of the steps of FIG. 6 may
be omitted, modified, or rearranged in order, for the methods and systems
provided herein.

[0176] As illustrated in FIG. 6, in some embodiments, the anode
electrolyte including an acid, e.g., hydrochloric acid or sulfuric acid,
and a depleted salt solution including low amount sodium ions, is
operatively connected to a system for further processing of the acid,
e.g., a mineral dissolution system 605 that is configured to dissolve
minerals and produce a mineral solution including calcium ions and/or
magnesium ions, e.g., mafic minerals such as olivine and serpentine. In
some embodiments, not shown in FIG. 6, the acid may be used for other
purposes in addition to or instead of mineral dissolution. Such uses
include, but are not limited to, use as a reactant in production of
cellulosic biofuels, use in the production of polyvinyl chloride (PVC),
and the like. System appropriate to such uses may be operatively
connected to the electrochemical unit, or the acid may be transported to
the appropriate site for use.

[0177] In some embodiments, the system further includes a water treatment
system configured for several uses, e.g., to dilute the brine, the
hydrochloric acid, the sulfuric acid, the cathode electrolyte, and/or
anode electrolyte. Such water treatment systems are described in U.S.
Patent Application Publication No. US 2010/0200419, filed 10 Feb. 2010,
which is incorporated herein by reference in its entirety.

[0178] In some embodiments, hydroxide ions, carbonate ions and/or
bicarbonate ions produced in the cathode electrolyte, and hydrochloric
acid or sulfuric acid produced in the anode electrolyte are removed from
the system, while sodium chloride or sodium sulfate in the salt solution
electrolyte is replenished to maintain continuous operation of the
system. As can be appreciated, in some embodiments, the system can be
configured to operate in various production modes including batch mode,
semi-batch mode, continuous flow mode, with or without the option to
withdraw portions of the hydroxide solution produced in the cathode
electrolyte, or withdraw all or a portion of the acid produced in the
anode electrolyte, or direct the hydrogen gas produced at the cathode to
the anode where it may be oxidized.

[0179] Depending on the flow rate of fluids into and out of the cathode
electrolyte, the concentration of the sodium hydroxide solution, and the
concentration of the bicarbonate solution in the cathode electrolyte, and
the pH of the cathode electrolyte may adjust, e.g., the pH may increase,
decrease or remain the same. In some embodiments, the pH of the cathode
electrolyte decreases after contacting with the bicarbonate solution.
Depending on the pH of the cathode electrolyte, the bicarbonate solution
contacted with the cathode electrolyte reacts with the sodium hydroxide
in the cathode electrolyte and reversibly dissociates and equilibrates to
produce water and carbonate ions in the cathode electrolyte compartment
as follows:

OH-+HCO3-<==>H2O+CO32-

[0180] The exiting solution from the cathode electrolyte may include
sodium hydroxide, bicarbonate ions, and/or carbonate ions. The overall
cell potential of the system can be determined through the Gibbs energy
change of the reaction by the formula:

Ecell=-ΔG/nF

or, at standard temperature and pressure conditions:

E°cell=-ΔG°/nF

where, Ecell is the cell voltage, ΔG is the Gibbs energy of
reaction, n is the number of electrons transferred, and F is the Faraday
constant (96485 J/Vmol). The Ecell of each of these reactions is pH
dependent based on the Nernst equestion.

[0181] Also, the overall cell potential can be determined through the
combination of Nernst equations for each half cell reaction:

E=E°-RT ln(Q)/nF

where, E° is the standard reduction potential, R is the universal
gas constant, (8.314 J/mol K), T is the absolute temperature, n is the
number of electrons involved in the half cell reaction, F is Faraday's
constant (96485 J/V mol), and Q is the reaction quotient such that:

Etotal=Ecathode+Eanode

[0182] When hydrogen is oxidized to protons at the anode as follows:

H2=2H++2e-,

E° is 0.00 V, n is 2, and Q is the square of the activity of
H+ so that:

Eanode=+0.059 pHa,

where pHa is the pH of the anode electrolyte.

[0183] When water is reduced to hydroxide ions and hydrogen gas at the
cathode as follows:

2H2O+2e-=H2+2OH-,

E° is -0.83 V, n is 2, and Q is the square of the activity of
OH- so that:

Ecathode=-0.059 pHc,

where pHc is the pH of the cathode electrolyte.

[0184] The E for the cathode and the anode reactions varies with the pH of
the anode and cathode electrolytes. Thus, if the anode reaction, which is
occurring in an acidic environment, is at a pH of 0, then the E of the
reaction is 0V for the half cell reaction. For the cathode reaction, if
the generation of bicarbonate ions occur at a pH of 7, then the
theoretical E is 7×(-0.059 V)=-0.413V for the half cell reaction
where a negative E means energy is needed to be input into the half cell
or full cell for the reaction to proceed. Thus, if the anode pH is 0 and
the cathode pH is 7 then the overall cell potential would be -0.413V,
where:

Etotal=-0.059 (pHa-pHc)=-0.059 ΔpH.

[0185] Thus, in some embodiments, directing bicarbonate solution into the
cathode electrolyte may lower the pH of the cathode electrolyte by
producing bicarbonate ions and/or carbonate ions in the cathode
electrolyte, which consequently may lower the voltage across the anode
and cathode.

[0186] Thus, as can be appreciated, if the cathode electrolyte is allowed
to increase to a pH of 14 or greater, the difference between the anode
half-cell potential and the cathode half cell potential will increase to
0.83V. With increased duration of cell operation without bicarbonate
solution addition or other intervention, e.g., diluting with water, the
required cell potential will continue to increase. The cell potential may
also increase due to ohmic resistance losses across the membranes in the
electrolyte and the cell's overvoltage potential. Herein, an overvoltage
potential includes the voltage difference between a thermodynamically
determined half-cell reduction potential, and the experimentally observed
potential at which the redox reaction occurs. The overvoltage potential
is related to cell voltage efficiency as the overvoltage potential
requires more energy than is thermodynamically required to drive a
reaction. In each case, the extra energy is lost as heat. Overvoltage
potential is specific to each cell design and will vary between cells and
operational conditions even for the same reaction.

[0187] In one aspect, the methods provided herein include one or more of
the following steps: contacting an anode with an anode electrolyte,
contacting a cathode with a cathode electrolyte, contacting a bicarbonate
solution with the cathode electrolyte, and applying a voltage across the
anode and the cathode. The bicarbonate solution is contacted with the
cathode electrolyte inside the cathode chamber and/or outside the cathode
chamber. The methods provided herein include producing an alkaline
solution in the cathode electrolyte by applying a voltage of less that
3V, or less than 2V, or less than 1V, or between 0.05-1V across the
cathode and an anode without producing a gas at the anode. In some
embodiments of the method, a first cation exchange membrane is
partitioned between the anode electrolyte and the cathode electrolyte. In
some embodiments of the method, the alkaline solution in the cathode
electrolyte includes hydroxide ions and/or bicarbonate ions and/or
carbonate ions. In some embodiments of the method, the method further
includes producing the bicarbonate solution. In some embodiments of the
method, the method further includes treating the bicarbonate ions and/or
carbonate ions with the divalent cations to produce carbonate
compositions.

[0188] In one aspect, the methods provided herein include one or more of
the following steps: contacting an anode with an anode electrolyte,
contacting a cathode with a cathode electrolyte, contacting a bicarbonate
solution with the cathode electrolyte, and applying a voltage across the
anode and the cathode. The bicarbonate solution is contacted with the
cathode electrolyte inside the cathode chamber and/or outside the cathode
chamber. The methods provided herein include producing an alkaline
solution in the cathode electrolyte by applying a voltage of less that
3V, or less than 2V, or less than 1V, or between 0.05-1V across the
cathode and an anode without producing a gas at the anode. In some
embodiments of the method, a first cation exchange membrane is
partitioned between the anode electrolyte and the cathode electrolyte. In
some embodiments of the method, the anode is in contact with a second
cation exchange membrane that separates the anode from the anode
electrolyte. In some embodiments of the method, the alkaline solution in
the cathode electrolyte includes hydroxide ions and/or bicarbonate ions
and/or carbonate ions. In some embodiments, the method provided herein
include one or more steps: the ambient air is excluded in the cathode
electrolyte; a pH of between and 7 and 14 or greater is maintained in the
cathode electrolyte; a pH of from less than 0 and up to 7 is maintained
in the anode electrolyte; hydrogen gas is oxidized at the anode to
produce hydrogen ions and hydrogen ions are migrated from the anode
through the second cation exchange membrane into the anode electrolyte;
hydroxide ions and hydrogen gas are produced at the cathode; hydroxide
ions are migrated from the cathode into the cathode electrolyte; hydrogen
gas is directed from the cathode to the anode; cations are migrated from
the anode electrolyte through the first cation exchange membrane into the
cathode electrolyte wherein the cations comprise sodium ions. In some
embodiments, the anions are migrated from the cathode electrolyte through
the anion exchange membrane into the anode electrolyte wherein the anions
include chloride ions. In some embodiments, the anions are migrated from
the sodium chloride solution through the anion exchange membrane into the
anode electrolyte and cations are migrated from the sodium chloride
through the first cation exchange membrane into the cathode electrolyte.

[0189] In some embodiments, the methods provided herein include one or
more of the following steps: applying a voltage across a cathode and a
gas diffusion anode in an electrochemical system, wherein the cathode
contacts a cathode electrolyte. In some embodiments, the method includes
providing hydrogen to the gas diffusion anode; contacting the cathode
with a cathode electrolyte; and applying a voltage across the anode and
cathode; directing hydrogen gas from the cathode to the anode;
interposing an anion exchange membrane between the anode electrolyte and
the salt solution; interposing a first cation exchange membrane between
the cathode electrolyte and the salt solution, where the salt solution is
contained between the anion exchange membrane and the first cation
exchange membrane; where anions migrate from the salt solution to the
anode electrolyte through the anion exchange membrane, and cations
migrate from the salt solution to the cathode electrolyte through the
first cation exchange membrane; producing hydroxide ions and/or carbonate
ions and/or bicarbonate ions in the cathode electrolyte; producing an
acid in the anode electrolyte; producing sodium hydroxide and/or sodium
carbonate and/or sodium bicarbonate in the cathode electrolyte; whereby
protons are migrated from the anode to the anode electrolyte; whereby
hydrochloric acid is produced in the anode electrolyte; producing
partially desalinated water from the salt solution; withdrawing a first
portion of the cathode electrolyte and contacting the portion of cathode
electrolyte with bicarbonate solution; and contacting the portion of
cathode electrolyte and the bicarbonate solution with a divalent cation
solution; whereby protons are produced at the anode and hydroxide ions
and hydrogen gas produced at the cathode; whereby a gas is not produced
at the anode when the voltage is applied across the anode and cathode;
where the voltage applied across the anode and cathode is less than 2V.

[0190] In some embodiments, hydroxide ions are formed at the cathode and
in the cathode electrolyte by applying a voltage of less than 2V across
the anode and cathode without forming a gas at the anode, while providing
hydrogen gas at the anode for oxidation at the anode. In some
embodiments, the methods do not form a gas at the anode when the voltage
applied across the anode and cathode is less than 3V or less, 2.9V or
less, 2.8V or less, 2.7V or less, 2.6V or less, 2.5V or less, 2.4V or
less, 2.3V or less, 2.2V or less, 2.1V or less, 2.0V or less, 1.9V or
less, 1.8V or less, 1.7V or less, 1.6V or less, 1.5V or less, 1.4V or
less, 1.3V or less, 1.2V or less, 1.1V or less, 1.0V or less, 0.9V or
less, 0.8V or less, 0.7V or less, 0.6V or less, 0.5V or less, 0.4V or
less, 0.3V or less, 0.2V or less, or 0.1V or less, or between 0.1V-3V, or
between 0.1V-2.5V, or between 0.1V-2V, or between 0.1V-1.5V, or between
0.1V-1V, or between 0.1V-0.5V, or between 0.05-1, or between 0.05-2V,
while hydrogen gas is provided to the anode where it is oxidized to
protons. As will be appreciated by one ordinarily skilled in the art, by
not forming a gas at the anode and by providing hydrogen gas to the anode
for oxidation at the anode; by adding bicarbonate solution to the cathode
electrolyte inside the cathode chamber; by controlling the resistance in
the system, for example, by decreasing the electrolyte path lengths; and
by selecting ionic membranes with low resistance and any other method
know in the art, hydroxide ions can be produced in the cathode
electrolyte with the lower voltages, as described herein.

[0191] In some embodiments, hydroxide ions, bicarbonate ions and carbonate
ions are produced in the cathode electrolyte where the voltage applied
across the anode and cathode is less than 3V or less, 2.9V or less, 2.8V
or less, 2.7V or less, 2.6V or less, 2.5V or less, 2.4V or less, 2.3V or
less, 2.2V or less, 2.1V or less, 2.0V or less, 1.9V or less, 1.8V or
less, 1.7V or less, 1.6V or less, 1.5V or less, 1.4V or less, 1.3V or
less, 1.2V or less, 1.1V or less, 1.0V or less, 0.9V or less, 0.8V or
less, 0.7V or less, 0.6V or less, 0.5V or less, 0.4V or less, 0.3V or
less, 0.2V or less, or 0.1V or less, or between 0.1V-3V, or between
0.1V-2.5V, or between 0.1V-2V, or between 0.1V-1.5V, or between 0.1V-1V,
or between 0.1V-0.5V, or between 0.05-1, or between 0.05-2V, without
forming a gas at the anode. In some embodiments, the method may be
adapted to withdraw and replenish at least a portion of the cathode
electrolyte and the acid in the anode electrolyte back into the system in
either a batch, semi-batch or continuous mode of operation.

[0192] In some embodiments, the method includes producing sodium hydroxide
and/or sodium carbonate ions and/or sodium bicarbonate ions in the
cathode electrolyte; producing an acid and a depleted salt solution in
the anode electrolyte including sodium ions and chloride ions; utilizing
the anode electrolyte to dissolve minerals and produce a mineral solution
comprising calcium ions and/or magnesium ions, wherein the minerals
comprises mafic minerals; filtering the mineral solution to produce a
filtrate comprising sodium ions and chloride ions; concentrating the
filtrate to produce the salt solution, wherein the concentrator comprises
a reverse osmosis system; utilizing the salt solution as the anode
electrolyte; precipitating a carbonate and/or bicarbonate with the
cathode electrolyte; wherein the carbonate and/or bicarbonate comprises
calcium and/or magnesium carbonate and/or bicarbonate. In some
embodiments, the method includes disposing of the acid in an underground
storage site where the acid can be stored in an un-reactive salt or rock
formation and hence does not cause an environmental acidification.

[0193] With reference to figures, the method in some embodiment includes
producing an acid in an electrochemical system and contacting a mineral
606 with the acid. In some embodiments, the method further produces the
acid in the anode electrolyte 203, without generating a gas at the anode
204, and oxidizing hydrogen gas 207 at the anode, wherein the acid
comprises hydrochloric acid 210; and wherein the hydrogen gas 207 is
produced at the cathode 201; producing an alkaline solution in the
cathode electrolyte 202; migrating sodium ions into the cathode
electrolyte; wherein the alkaline solution comprises sodium hydroxide,
sodium bicarbonate and/or sodium carbonate; wherein the voltage is less
than 2V or less than 1V; wherein the anode electrolyte 203 is separated
from the cathode electrolyte 202 by first cation exchange membrane 206;
wherein the anode 204 includes a second cation exchange membrane 212 in
contact with the anode electrolyte 203; wherein the anode electrolyte
comprises a salt, e.g., sodium chloride; dissolving a mineral 106 with
the acid 210 to produce a mineral solution; producing calcium ions and/or
magnesium ions; wherein the mineral comprises a mafic mineral, e.g.
olivine or serpentine; filtering the mineral solution to produce a
filtrate comprising sodium ions and chloride ions solution; concentrating
the filtrate to produce a salt solution; utilizing the salt solution as
the anode electrolyte 203; precipitating a carbonate and/or bicarbonate
with the cathode electrolyte 202 by contacting the divalent cations with
the cathode electrolyte; wherein the carbonate and/or bicarbonate
includes calcium and/or magnesium carbonate and/or bicarbonate. In some
embodiments, the method includes disposing of the acid in an underground
storage site where the acid can be stored in an un-reactive salt or rock
formation and hence does not cause an environmental acidification.

[0194] In some embodiments, the anode electrolyte and the cathode
electrolyte in the electrochemical cell, in the methods and systems
provided herein, are operated at room temperature or at elevated
temperatures, such as, e.g., at more than 40° C., or more than
50° C., or more than 60° C., or more than 70° C., or
more than 80° C., or between 30-70° C.

[0195] In some embodiments, the method further includes producing the
bicarbonate solution. In some embodiments of the method, the method
further includes treating the bicarbonate ions and/or carbonate ions with
the divalent cations to produce carbonate compositions. These methods
have been described in detail below.

[0196] In some embodiments, depending on the ionic species desired in the
cathode electrolyte and/or the anode electrolyte and/or the salt
solution, alternative reactants can be utilized. Thus, for example, if a
potassium salt such as potassium hydroxide or potassium carbonate is
desired in the cathode electrolyte, then a potassium salt such as
potassium chloride can be utilized in the salt solution. Similarly, if
sulfuric acid is desired in the anode electrolyte, then a sulfate such as
sodium sulfate can be utilized in the salt solution.

C. Methods and Systems to Produce Carbonate Compositions

[0197] The methods and systems provided herein are further configured to
process the sodium carbonate/sodium bicarbonate solution obtained after
the alkaline solution, such as, the cathode electrolyte is contacted with
the bicarbonate solution. As described herein, the bicarbonate solution
after being contacted with the alkaline solution, such as, sodium
hydroxide in the cathode electrolyte, results in carbonate formation.
Depending on the pH of the cathode electrolyte, the bicarbonate in the
bicarbonate solution may fully convert to carbonate or may partially
convert to carbonate. In some embodiments, more than 5%; or more than
10%; or more than 20%; or more than 30%; or more than 40%; or more than
50%; or more than 60%; or more than 70%; or more than 80%; or more than
90%; or between 5-99%; or between 5-90%; or between 5-80%; or between
5-70%; or between 5-60%; or between 5-50%; or between 5-40%; or between
5-30%; or between 5-20%; or between 5-10%; or between 10-99%; or between
10-90%; or between 10-80%; or between 10-70%; or between 10-60%; or
between 10-50%; or between 10-40%; or between 10-30%; or between 10-20%;
or between 20-99%; or between 20-90%; or between 20-80%; or between
20-70%; or between 20-60%; or between 20-50%; or between 20-40%; or
between 20-30%; or between 30-99%; or between 30-80%; or between 30-50%;
or between 50-99%; or between 50-90%; or between 50-70%; or between
60-99%; or between 60-90%; or between 60-80%; or between 60-70%; or
between 70-99%; or between 70-90%; or between 70-80%; or between 80-99%;
or between 80-90%; or between 90-99%; or between 90-95%; of the
bicarbonate converts to carbonate when the bicarbonate solution is
contacted with the alkaline solution, such as, sodium hydroxide in the
cathode electrolyte.

[0198] With reference to FIGS. 2A, 2B, 3A, 3B, 4A, 4B, 5A, and 5B, in some
embodiments, the system is configured for further processing of the
cathode electrolyte 202 after the cathode electrolyte is contacted with
the bicarbonate solution 205 outside and/or inside the cathode chamber.
As illustrated in FIG. 6, the system is configured with a precipitator
603 to precipitate carbonates and/or bicarbonates from the solution using
divalent cations, e.g., calcium, magnesium, or combination thereof. In
some embodiments, the solution obtained after the contacting of the
alkaline solution, such as, the cathode electrolyte with the bicarbonate
solution, is subjected to the precipitation conditions in the
precipitator. The solution obtained after the contacting of the cathode
electrolyte with the bicarbonate solution includes sodium hydroxide
and/or sodium carbonate, and/or sodium bicarbonate.

[0199] The divalent cations include any solid or solution that contains
divalent cations, such as, alkaline earth metal ions or any aqueous
medium containing alkaline earth metals. The alkaline earth metals
include calcium, magnesium, strontium, barium, etc. or combinations
thereof. The divalent cations (e.g., alkaline earth metal cations such as
Ca2+ and Mg2+) may be found in industrial wastes, seawater,
brines, hard water, minerals, and many other suitable sources. The
alkaline-earth-metal-containing water includes fresh water or saltwater,
depending on the method employing the water. In some embodiments, the
water employed in the process includes one or more alkaline earth metals,
e.g., magnesium, calcium, etc. In some embodiments, the alkaline earth
metal ions are present in an amount of 1% to 99% by wt; or 1% to 95% by
wt; or 1% to 90% by wt; or 1% to 80% by wt; or 1% to 70% by wt; or 1% to
60% by wt; or 1% to 50% by wt; or 1% to 40% by wt; or 1% to 30% by wt; or
1% to 20% by wt; or 1% to 10% by wt; or 20% to 95% by wt; or 20% to 80%
by wt; or 20% to 50% by wt; or 50% to 95% by wt; or 50% to 80% by wt; or
50% to 75% by wt; or 75% to 90% by wt; or 75% to 80% by wt; or 80% to 90%
by wt of the solution containing the alkaline earth metal ions. In some
embodiments, the alkaline earth metal ions are present in saltwater, such
as, seawater. In some embodiments, the source of divalent cations is hard
water or naturally occurring hard brines. In some embodiments, calcium
rich waters may be combined with magnesium silicate minerals, such as
olivine or serpentine.

[0201] Freshwater may be a convenient source of cations (e.g., cations of
alkaline earth metals such as Ca2+ and Mg2+). Any of a number
of suitable freshwater sources may be used, including freshwater sources
ranging from sources relatively free of minerals to sources relatively
rich in minerals. Mineral-rich freshwater sources may be naturally
occurring, including any of a number of hard water sources, lakes, or
inland seas. Some mineral-rich freshwater sources such as alkaline lakes
or inland seas (e.g., Lake Van in Turkey) also provide a source of
pH-modifying agents. Mineral-rich freshwater sources may also be
anthropogenic. For example, a mineral-poor (soft) water may be contacted
with a source of cations such as alkaline earth metal cations (e.g.,
Ca2+, Mg2+, etc.) to produce a mineral-rich water that is
suitable for methods and systems described herein. Cations or precursors
thereof (e.g., salts, minerals) may be added to freshwater (or any other
type of water described herein) using any convenient protocol (e.g.,
addition of solids, suspensions, or solutions). In some embodiments,
divalent cations selected from Ca2+ and Mg2+ are added to
freshwater. In some embodiments, freshwater comprising Ca2+ is
combined with magnesium silicates (e.g., olivine or serpentine), or
products or processed forms thereof, yielding a solution comprising
calcium and magnesium cations.

[0202] In some embodiments, as illustrated in FIGS. 2A, 3A, 4A, and 5A,
where the bicarbonate solution is contacted with the cathode electrolyte
inside the cathode chamber, the system is configured to treat bicarbonate
and/or carbonate ions in the cathode electrolyte with a divalent cation
selected from the group consisting of calcium, magnesium, and combination
thereof. In some embodiments, bicarbonate and/or carbonate ions in the
cathode electrolyte can be treated with the divalent cations inside the
cathode chamber where a solution containing the divalent cations is added
to the cathode electrolyte after the addition of the bicarbonate solution
to the cathode chamber. In some embodiments, bicarbonate and/or carbonate
ions in the cathode electrolyte react with the divalent cations inside
the cathode chamber when the cathode electrolyte already includes
divalent cations, such as seawater. In some embodiments, bicarbonate
and/or carbonate ions in the cathode electrolyte can be treated with the
divalent cations outside the cathode chamber, e.g. in a precipitator,
where the cathode electrolyte containing the hydroxide, bicarbonate
and/or carbonate is withdrawn from the cathode chamber and is treated
with the divalent cations outside the cathode chamber.

[0203] In some embodiments, as illustrated in FIGS. 2B, 3B, 4B, and 5B,
where the bicarbonate solution is contacted with the cathode electrolyte
outside the cathode chamber, the system is configured to treat
bicarbonate and/or carbonate ions in the solution with a divalent cation
selected from the group consisting of calcium, magnesium, and combination
thereof. In embodiments where the solution is obtained after the
contacting of the cathode electrolyte with the bicarbonate solution
outside the cathode chamber, the solution is mixed with the divalent
cations in a precipitator. In some embodiments, the cathode electrolyte,
the bicarbonate solution, and the divalent cations are all mixed in the
precipitator outside the cathode chamber to precipitate the carbonate
materials.

[0204] The precipitator can be a tank or a series of tanks Contact
protocols include, but are not limited to, direct contacting protocols,
e.g., flowing the bicarbonate solution through the volume of water
containing cations, e.g. alkaline earth metal ions and through the volume
of cathode electrolyte containing sodium hydroxide; concurrent contacting
means, e.g., contact between unidirectionally flowing liquid phase
streams; and countercurrent means, e.g., contact between oppositely
flowing liquid phase streams, and the like. Thus, contact may be
accomplished through use of infusers, bubblers, fluidic Venturi reactor,
sparger, gas filter, spray, tray, or packed column reactors, and the
like, as may be convenient. In some embodiments, the contact is by spray.
In some embodiments, the contact is through packed column. In some
embodiments, the bicarbonate solution is added to the source of cations
and the cathode electrolyte containing sodium hydroxide. In some
embodiments, the source of cations and the cathode electrolyte containing
sodium hydroxide is added to the bicarbonate solution. In some
embodiments, both the source of cations and the bicarbonate solution are
simultaneously added to the cathode electrolyte containing sodium
hydroxide in the precipitator for precipitation.

[0205] In some embodiments, where the bicarbonate solution has been added
to the cathode electrolyte inside the cathode chamber, the withdrawn
cathode electrolyte including sodium hydroxide, sodium bicarbonate and/or
sodium carbonate is administered to the precipitator for further reaction
with the divalent cations. In some embodiments, where the bicarbonate
solution and the divalent cations have been added to the cathode
electrolyte inside the cathode chamber, the withdrawn cathode electrolyte
including sodium hydroxide, calcium carbonate, magnesium carbonate,
calcium bicarbonate, magnesium bicarbonate, calcium magnesium carbonate,
or combination thereof, is administered to the precipitator for further
processing.

[0206] The precipitate obtained after the contacting of the bicarbonate
solution with the cathode electrolyte and the divalent cations includes
calcium carbonate, magnesium carbonate, calcium bicarbonate, magnesium
bicarbonate, calcium magnesium carbonate, or combination thereof. In some
embodiments, the precipitate may be subjected to one or more of steps
including, but not limited to, dewatering, washing of the precipitate,
dewatering of the washed precipitate, drying, milling, storing, to make
the carbonate composition of the invention.

[0207] In some embodiments, the processing of the precipitate is as
illustrated in FIG. 7. The precipitator containing the solution of
calcium carbonate, magnesium carbonate, calcium bicarbonate, magnesium
bicarbonate, calcium magnesium carbonate, or combination thereof is
subjected to precipitation conditions. At precipitation step, carbonate
compounds, which may be amorphous or crystalline, are precipitated. These
carbonate compounds may form a reaction product comprising carbonic acid,
bicarbonate, carbonate, or mixture thereof. The carbonate precipitate may
be the self-cementing composition and may be stored as is in the mother
liquor or may be further processed to make the cement products.
Alternatively, the precipitate may be subjected to further processing to
give the hydraulic cement or the supplementary cementitious materials
(SCM) compositions. The self-cementing compositions, hydraulic cements,
and SCM have been described in U.S. application Ser. No. 12/857,248,
filed 16 Aug. 2010, which is incorporated herein by reference in its
entirety.

[0208] The one or more conditions or one or more precipitation conditions
of interest include those that change the physical environment of the
water to produce the desired precipitate product. Such one or more
conditions or precipitation conditions include, but are not limited to,
one or more of temperature, pH, precipitation, dewatering or separation
of the precipitate, drying, milling, and storage. For example, the
temperature of the water may be within a suitable range for the
precipitation of the desired composition to occur. For example, the
temperature of the water may be raised to an amount suitable for
precipitation of the desired carbonate compound(s) to occur. In such
embodiments, the temperature of the water may be from 5 to 70° C.,
such as from 20 to 50° C., and including from 25 to 45° C.
As such, while a given set of precipitation conditions may have a
temperature ranging from 0 to 100° C., the temperature may be
raised in certain embodiments to produce the desired precipitate. In
certain embodiments, the temperature is raised using energy generated
from low or zero carbon dioxide emission sources, e.g., solar energy
source, wind energy source, hydroelectric energy source, etc.

[0209] The residence time of the precipitate in the precipitator before
the precipitate is removed from the solution, may vary. In some
embodiments, the residence time of the precipitate in the solution is
more than 5 seconds, or between 5 seconds-1 hour, or between 5 seconds-1
minute, or between 5 seconds to 20 seconds, or between 5 seconds to 30
seconds, or between 5 seconds to 40 seconds. Without being limited by any
theory, it is contemplated that the residence time of the precipitate may
affect the size of the particle. For example, a shorter residence time
may give smaller size particles or more disperse particles whereas longer
residence time may give agglomerated or larger size particles. In some
embodiments, the residence time in the process of the invention may be
used to make small size as well as large size particles in a single or
multiple batches which may be separated or may remain mixed for later
steps of the process.

[0210] The nature of the precipitate may also be influenced by selection
of appropriate major ion ratios. Major ion ratios may have influence on
polymorph formation, such that the carbonate products are metastable
forms, such as, but not limited to vaterite, aragonite, amorphous calcium
carbonate, or combination thereof. In some embodiments, the carbonate
products may also include calcite. Such polymorphic precipitates are
described in U.S. application Ser. No. 12/857,248, filed 16 Aug. 2010,
which is incorporated herein by reference in its entirety. For example,
magnesium may stabilize the vaterite and/or amorphous calcium carbonate
in the precipitate. Rate of precipitation may also influence compound
polymorphic phase formation and may be controlled in a manner sufficient
to produce a desired precipitate product. The most rapid precipitation
can be achieved by seeding the solution with a desired polymorphic phase.
Without seeding, rapid precipitation can be achieved by rapidly
increasing the pH of the sea water. The higher the pH is, the more rapid
the precipitation may be.

[0211] In some embodiments, a set of conditions to produce the desired
precipitate from the water include, but are not limited to, the water's
temperature and pH, and in some instances the concentrations of additives
and ionic species in the water. Precipitation conditions may also include
factors such as mixing rate, forms of agitation such as ultrasonics, and
the presence of seed crystals, catalysts, membranes, or substrates. In
some embodiments, precipitation conditions include supersaturated
conditions, temperature, pH, and/or concentration gradients, or cycling
or changing any of these parameters. The protocols employed to prepare
carbonate compound precipitates according to the invention may be batch
or continuous protocols. It will be appreciated that precipitation
conditions may be different to produce a given precipitate in a
continuous flow system compared to a batch system.

[0212] Following production of the carbonate precipitate from the water,
the resultant precipitated carbonate composition may be separated from
the mother liquor or dewatered to produce the precipitate product, as
illustrated at step 702 of FIG. 7. Alternatively, the precipitate is left
as is in the mother liquor or mother suprenate and is used as a cementing
composition. Separation of the precipitate can be achieved using any
convenient approach, including a mechanical approach, e.g., where bulk
excess water is drained from the precipitated, e.g., either by gravity
alone or with the addition of vacuum, mechanical pressing, by filtering
the precipitate from the mother liquor to produce a filtrate, etc.
Separation of bulk water produces a wet, dewatered precipitate. The
dewatering station may be any number of dewatering stations connected to
each other to dewater the slurry (e.g., parallel, in series, or
combination thereof).

[0213] The above protocol results in the production of slurry of the
precipitate and mother liquor. This precipitate in the mother liquor
and/or in the slurry may give the self-cementing composition. In some
embodiments, a portion or whole of the dewatered precipitate or the
slurry is further processed to make the hydraulic cement or the SCM
compositions.

[0214] Where desired, the compositions made up of the precipitate and the
mother liquor may be stored for a period of time following precipitation
and prior to further processing. For example, the composition may be
stored for a period of time ranging from 1 to 1000 days or longer, such
as 1 to 10 days or longer, at a temperature ranging from 1 to 40°
C., such as 20 to 25° C.

[0215] The slurry components are then separated. Embodiments may include
treatment of the mother liquor, where the mother liquor may or may not be
present in the same composition as the product. The resultant mother
liquor of the reaction may be disposed of using any convenient protocol.
In certain embodiments, it may be sent to a tailings pond for disposal.
In certain embodiments, it may be disposed of in a naturally occurring
body of water, e.g., ocean, sea, lake or river. In certain embodiments,
the mother liquor is returned to the source of feedwater for the methods
of invention, e.g., an ocean or sea. Alternatively, the mother liquor may
be further processed, e.g., subjected to desalination protocols, as
described further in U.S. application Ser. No. 12/163,205, filed Jun. 27,
2008; the disclosure of which is herein incorporated by reference.

[0216] The resultant dewatered precipitate is then dried to produce the
carbonate composition of the invention, as illustrated at step 704 of
FIG. 7. Drying can be achieved by air drying the precipitate. Where the
precipitate is air dried, air drying may be at a temperature ranging from
-70 to 120° C., as desired. In certain embodiments, drying is
achieved by freeze-drying (i.e., lyophilization), where the precipitate
is frozen, the surrounding pressure is reduced and enough heat is added
to allow the frozen water in the material to sublime directly from the
frozen precipitate phase to gas. In yet another embodiment, the
precipitate is spray dried to dry the precipitate, where the liquid
containing the precipitate is dried by feeding it through a hot gas (such
as the gaseous waste stream from the power plant), e.g., where the liquid
feed is pumped through an atomizer into a main drying chamber and a hot
gas is passed as a co-current or counter-current to the atomizer
direction. Depending on the particular drying protocol of the system, the
drying station may include a filtration element, freeze drying structure,
spray drying structure, etc.

[0217] In some embodiments, the step of spray drying may include
separation of different sized particles of the precipitate. Where
desired, the dewatered precipitate product from 702 may be washed before
drying, as illustrated at step 703 of FIG. 7. The precipitate may be
washed with freshwater, e.g., to remove salts (such as NaCl) from the
dewatered precipitate. Used wash water may be disposed of as convenient,
e.g., by disposing of it in a tailings pond, etc. The water used for
washing may contain metals, such as, iron, nickel, etc.

[0218] As illustrated in FIG. 7, at step 705, the dried precipitate is
refined, milled, aged, and/or cured, e.g., to provide for desired
physical characteristics, such as particle size, surface area, zeta
potential, etc., or to add one or more components to the precipitate,
such as admixtures, aggregate, supplementary cementitious materials,
etc., to produce the carbonate composition. Refinement may include a
variety of different protocols. In certain embodiments, the product is
subjected to mechanical refinement, e.g., grinding, in order to obtain a
product with desired physical properties, e.g., particle size, etc. The
dried precipitate may be milled or ground to obtain a desired particle
size.

[0219] The cementitous composition, thus formed, has elements or markers
that originate from the bicarbonate solution used in the process. The
composition after setting, and hardening has a compressive strength of at
least 14 MPa; or at least 16 MPa; or at least 18 MPa; or at least 20 MPa;
or at least 25 MPa; or at least 30 MPa; or at least 35 MPa; or at least
40 MPa; or at least 45 MPa; or at least 50 MPa; or at least 55 MPa; or at
least 60 MPa; or at least 65 MPa; or at least 70 MPa; or at least 75 MPa;
or at least 80 MPa; or at least 85 MPa; or at least 90 MPa; or at least
95 MPa; or at least 100 MPa; or from 14-100 MPa; or from 14-80 MPa; or
from 14-75 MPa; or from 14-70 MPa; or from 14-65 MPa; or from 14-60 MPa;
or from 14-55 MPa; or from 14-50 MPa; or from 14-45 MPa; or from 14-40
MPa; or from 14-35 MPa; or from 14-30 MPa; or from 14-25 MPa; or from
14-20 MPa; or from 14-18 MPa; or from 14-16 MPa; or from 17-35 MPa; or
from 17-30 MPa; or from 17-25 MPa; or from 17-20 MPa; or from 17-18 MPa;
or from 20-100 MPa; or from 20-90 MPa; or from 20-80 MPa; or from 20-75
MPa; or from 20-70 MPa; or from 20-65 MPa; or from 20-60 MPa; or from
20-55 MPa; or from 20-50 MPa; or from 20-45 MPa; or from 20-40 MPa; or
from 20-35 MPa; or from 20-30 MPa; or from 20-25 MPa; or from 30-100 MPa;
or from 30-90 MPa; or from 30-80 MPa; or from 30-75 MPa; or from 30-70
MPa; or from 30-65 MPa; or from 30-60 MPa; or from 30-55 MPa; or from
30-50 MPa; or from 30-45 MPa; or from 30-40 MPa; or from 30-35 MPa; or
from 40-100 MPa; or from 40-90 MPa; or from 40-80 MPa; or from 40-75 MPa;
or from 40-70 MPa; or from 40-65 MPa; or from 40-60 MPa; or from 40-55
MPa; or from 40-50 MPa; or from 40-45 MPa; or from 50-100 MPa; or from
50-90 MPa; or from 50-80 MPa; or from 50-75 MPa; or from 50-70 MPa; or
from 50-65 MPa; or from 50-60 MPa; or from 50-55 MPa; or from 60-100 MPa;
or from 60-90 MPa; or from 60-80 MPa; or from 60-75 MPa; or from 60-70
MPa; or from 60-65 MPa; or from 70-100 MPa; or from 70-90 MPa; or from
70-80 MPa; or from 70-75 MPa; or from 80-100 MPa; or from 80-90 MPa; or
from 80-85 MPa; or from 90-100 MPa; or from 90-95 MPa; or 14 MPa; or 16
MPa; or 18 MPa; or 20 MPa; or 25 MPa; or 30 MPa; or 35 MPa; or 40 MPa; or
45 MPa. For example, in some embodiments of the foregoing aspects and the
foregoing embodiments, the composition after setting, and hardening has a
compressive strength of 14 MPa to 40 MPa; or 17 MPa to 40 MPa; or 20 MPa
to 40 MPa; or 30 MPa to 40 MPa; or 35 MPa to 40 MPa. In some embodiments,
the compressive strengths described herein are the compressive strengths
after 1 day, or 3 days, or 7 days, or 28 days.

[0220] The precipitates, comprising, e.g., calcium and magnesium
carbonates and bicarbonates in some embodiments may be utilized as
building materials, e.g., as cements and aggregates, as described in
commonly assigned U.S. patent application Ser. No. 12/126,776, filed on
23 May 2008, herein incorporated by reference in its entirety.

[0221] The following examples are put forth so as to provide those of
ordinary skill in the art with a complete disclosure and description of
how to make and use the present invention, and are not intended to limit
the scope of what the inventors regard as their invention nor are they
intended to represent that the experiments below are all or the only
experiments performed. Efforts have been made to ensure accuracy with
respect to numbers used (e.g. amounts, temperature, etc.) but some
experimental errors and deviations should be accounted for. Unless
indicated otherwise, parts are parts by weight, molecular weight is
weight average molecular weight, temperature is in degrees Centigrade,
and pressure is at or near atmospheric.

EXAMPLES

Example 1

[0222] In an exemplary embodiment, a system configured substantially as
illustrated in FIG. 2A, 2B, 3A, 3B, 4A, 4B, 5A, or 5B is operated with a
constant current density applied across the electrodes at steady state
conditions while bicarbonate solution is continuously dissolved into the
cathode electrolyte, at various temperatures and voltages. In the system,
a platinum catalyst, gas diffusion anode obtained from E-TEK Corporation,
(USA) is used as the anode. A Raney nickel deposited onto a nickel gauze
substrate is used as the cathode. In the system, the initial acid
concentration in the anode electrolyte is 1 M; the initial sodium
chloride salt solution is 5 M; and the initial concentration of the
sodium hydroxide solution in the cathode compartment is 1 M. In the
system, the pH of the cathode compartment is maintained at either 8 or 10
by regulating the amount of bicarbonate solution contacted with the
cathode electrolyte.

[0223] As is illustrated in Table III, a range of current densities is
achieved across the electrode in the system. As can be appreciated, the
current density that can be achieved with other configurations of the
system may vary, depending on several factors including the cumulative
electrical resistance losses in the cell, environmental test conditions,
the over-potential associated with the anodic and cathodic reactions, and
other factors.

[0224] The current densities achieved in the present configuration and as
set forth in Table III are correlated with the production of hydroxide
ions at the cathode, and thus are correlated with the production of
sodium hydroxide and/or sodium carbonate and/or sodium bicarbonate in the
cathode electrolyte, as follows. With reference to Table III, at
75° C., 0.8 V and a pH of 10, each cm2 of electrode passes
13.3 mA of current, where current is a measure of charge passed (Coulomb)
per time (second). Based on Faraday's Laws, the amount of product, e.g.,
hydroxide ions, produced at an electrode is proportional to the total
electrical charge passed through the electrode as follows:

n=(I*t)/(F*z)

where n is moles of product, I is a current, t is time, F is Faraday's
constant, and z is the electrons transferred per product ionic species
(or reagent ionic species). Thus, based on the present example,
1.38×10-4 moles of hydroxide ions are produced per second per
cm2 of electrode, which is correlated with the production of sodium
hydroxide in the cathode electrolyte. In the system, the production rate
of NaOH dictates the production rate of NaHCO3 and Na2CO3
through Le Chatelier's principle following the net chemical equilibria
equations of

HCO3-+OH-═H2O+CO32-,

where an increase in concentration of one species in equilibria will
change the concentration of all species so that the equilibrium product
maintains the equilibrium constant.

[0225] In the system, as illustrated in FIGS. 2A, 2B, 3A, 3B, 4A, 4B, 5A,
and 5B, the voltage across the cathode and the anode is dependent on
several factors including the pH difference between the anode electrolyte
and cathode electrolyte. Thus, in some embodiments the system can be
configured to operate at a specified pH and voltage; react bicarbonate
solution with the sodium hydroxide in the cathode electrolyte; and
produce carbonate ions in the cathode electrolyte. In these embodiments
the pH of the cathode electrolyte solution may decrease, remain the same,
or increase, depending on the rate of removal of protons compared to rate
of introduction of the bicarbonate solution.

[0226] The carbonate ion containing solution is recovered from the cathode
electrolyte and is reacted with divalent cations to result in the
carbonate composition of the invention. The carbonate composition is
processed as described herein to result in the cementitious compositions
of the invention which are further used to form formed building
materials, aggregates, and concrete.